List of Aliens in Ben 10

This is the list of all aliens of the Omnitrix and Ultimatrix showed in the Ben 10 universe

Heatblast
Heatblast is a Pyronite (pyro meaning fire and "nite" as in ignite) from the star Pyros. Heatblast is Ben's first transformation, accidentally activated in the pilot episode of the original series, "And Then There Were 10" when Ben was trying to remove the Omnitrix immediately after it first attached to him. Heatblast is a magma-based life-form that can control fire at will, either projecting it in a wide range of forms or absorbing it into himself. He can fire streams of flame, create fireballs, manifest tornadoes of flame, utilize those tornadoes to carry himself and others short distances, and radiate heat in all directions for a localized explosion. He can also achieve flight by firing at the ground to propel himself like a rocket. Apart from this, Heatblast is also a highly durable alien, able to endure being thrown through buildings without being slowed. When Ben gets a cold, Heatblast's powers are reversed, giving him cryokinetic (cold and ice) powers instead of the normal pyrokinesis (heat and flame). Heatblast's powers can be negated by sufficient amounts of water or similar fire-extinguishing materials and large amounts of water can extinguish him permanently. He is also unable to lower his own body temperature, which prevents him from touching things without burning them, people included. Ben's 10-year-old version of Heatblast made an appearance in the Ultimate Alien episode "The Forge of Creation". His look was slightly altered; his rock was redder, and his hands and the spaces between the rocks became a more solid color of yellow. The Omnitrix badge also changed from white to green. Heatblast also reappears through the Ultimatrix, the first for 16-year old Ben, in "Viktor: The Spoils" to defeat King Xarion (in Dr. Viktor's body), and now has a darker skintone, similar to Alan Albright. Ben 10,000 used his powers in the Ultimate Alien episode "Ben 10,000 Returns" to fight Eon and his servants. Heatblast appears as a playable alien form in Ben 10 video games Protector of Earth and Galactic Racing.
 * Steven Blum - Ben 10
 * Michael Reisz - Ben 10 (As Kevin in "Kevin 11")
 * Charlie Schlatter - Ben 10 (As Kevin in "Framed")
 * Grey DeLisle - Ben 10 (As Gwen in "Gwen 10")
 * David Franklin - Ben 10: Race Against Time
 * Dee Bradley Baker - Ben 10: Ultimate Alien

Wildmutt
Wildmutt is a Vulpimancer from the garbage planet Vulpin (which means fox), a vaguely dog-like alien beast whose physical features are a cross between a lion and a gorilla. Though able to fight with animalistic speed and strength, Wildmutt has no eyes and thus relies on gills on his neck for thermographic echo location, both his senses of sound and smell, his smell is more advanced than humans. However, his only weaknesses are anything that can overwhlem his senses like a loud sound or a horrific smell. According to various profiles on Wildmutt, the porcupine-like quills on his back supplement his radar sight and can also serve as weapons, either protecting Wildmutt while he's rolling, or as projectiles fired off at will. This ability is unique to adult Vulpimancers, and since Ben's version is only ten years old, these quills have not fully developed. Ben first transformed into Wildmutt in "And Then There Were 10" after his second experiment with the Omnitrix, thus his first intentional transformation. In Ben 10: Ultimate Alien, Wildmutt's design was basically unchanged, except that his lips were orange instead of black and he has Ultimatrix symbol on his chest. As Ultimate Wildmutt, gaining the ability to speak, he is a red-skinned version of himself with bony spikes protruding from his back, and a stinger-like spike on the end of his tail. He first appears in "Prisoner #775 is Missing" when he manages to subdue Prisoner #775.
 * Dee Bradley Baker - Ben 10 and Ben 10: Ultimate Alien (vocal effects)

Diamondhead
Diamondhead is a Petrosapien ("Petro-" referring to rocks, "sapien" referring to an intelligent being; Petrosapien would then mean "intelligent rock") from the planet Petropia (a combination of the Greek "Petro-" and "topos", forming a word similar to "rock place"). The planet was destroyed by Vilgax with a help of Tetrax, who unknowingly helped him create the weapon that destroyed his home. This was originally the case, but in Ben 10: Alien Force, at the episode "The Secret of Chromastone", it was revealed that the object used to destroy Petropia was a crystal that must be used by Sugilite (the Crystalsapien whose DNA was used for the sample of Chromastone) to recreate the planet. Petropia was reborn in this episode, and all Petrosapiens now resemble Ben's Diamondhead form (all but Tetrax, as he was off world watching the destruction of his planet from Vilgax's ship, the Chimerean Hammer). Diamondhead's body is composed of an extremely durable organic crystal, making him nearly invulnerable. Diamondhead can control his crystal physiology at will, allowing him to create crude crystal weapons from any part of his body on demand or fire crystal shards from his hands. This same ability also allows him to regenerate to an extent, such as re-growing lost limbs. In addition to growing crystal from himself, Diamondhead can grow crystal over other objects. Lasers and other similar weapons are useless against Diamondhead, as his crystal body acts as a prism, refracting the beams. The one drawback to Diamondhead's crystal form is the crystal itself, which can shatter if exposed to sufficiently strong sonic vibrations. While Petrosapiens can regenerate limbs, there is a limit to how much damage they can recover from. Ben first transforms into Diamondhead in "And Then There Were 10" when he needed to destroy one of Vilgax's giant robot. In the planning stages, Diamondhead was set up to be one of the aliens Ben would have discovered later on, while Cannonbolt would have been one of the original ten. In Ben 10: Alien Force, Diamondhead was regained after Chromastone was temporarily destroyed by Vilgax. He no longer wears a costume, instead having a body composed of material similar to that of Chromastone, and the Omnitrix/Ultimatrix symbol moves to his chest from his left-chest. He, against orders of Magister Hulka, returns in Ultimate Alien during the episode "Basic Training," where he is used to grab a dummy he, Kevin, and Gwen were saving from Brannigan. In "Ben 10,000 Returns," Ben 10,000 used him to guard Ben (diamonds don't tend to age, Ben 10,000 says) from Eon's time ray, and a few more times towards the end of the episode to fend off Eon so 16-year old Ben could destroy the Hand of Armaggedon.
 * Jim Ward - Ben 10
 * Charlie Schlatter - Ben 10 (As Kevin in "Framed")
 * Vanessa Marshall - Ben 10 (As Gwen in "Gwen 10")
 * Daran Norris - Ben 10: Race Against Time
 * Dee Bradley Baker - Ben 10: Alien Force and Ben 10: Ultimate Alien)

XLR8
XLR8 is a Kinecceleran (a portmanteau of the words "kinetic" and "accelerate") from the planet Kinet (the first part of kinetic, which is movement energy). XLR8 resembles a slender semi-armored velociraptor, the base creature for the form's design. XLR8 has wheel-shaped feet and wears a helmet with a windshield, which is part of his alien biology, leaving the features of his head unknown. XLR8 has the ability to manipulate friction to reach speeds of 300 mph in an instant, and the same power allows him to climb up walls and run on water with relative ease. Using his speed, XLR8 can perform a number of unique feats. He can create tornadoes through centrifugal force, either through running in a small circle or spinning, and can deliver speed-enhanced attacks in rapid succession. Amazing reflexes accompany this speed, allowing XLR8 to quickly dodge attacks with relative ease. His scissor-like claws can also cut through objects. XLR8 never had such problems like these however. Ben first transformed into XLR8 in "And Then There Were 10" when he decided to play around a bit with his newfound power, using the form to get revenge on Cash and JT which he fought with earlier in the episode. XLR8 appears as a playable alien form in "Ben 10: Protector of Earth". He was used by Ben 10,000 during the Ultimate Alien episode "Ben 10,000 Returns." His appearance was not shown as Ben used the Ultimate Ben feature, but his hologram seemed to be spot-on with his original.
 * Jim Ward - Ben 10

Grey Matter
Grey Matter is a Galvan (the former a play on actual grey matter and Greys, the latter a play on galvanization) from the planet Galvan Prime, where the Omnitrix was originally built. Grey Matter is an alien who is 6 inches tall who has a great amount of calculative and technical intellect. He can create almost anything from spare parts and deduce the function of any device at a glance. Also, Grey Matter's intellect serves as a problem solver and analytical help in difficult situations. Grey Matter's size allows him to squeeze into small spaces, and he can climb walls due to the tiny suction cups on his skin. He also has sharp teeth, and his slimy skin makes him difficult to grab. Unfortunately, Grey Matter's size makes him unsuitable for battle, and hence Ben must outsmart his enemies while using the form. Grey Matter has, however, proved very valuable when used, as he is capable of hiding in very tightly compacted areas, and the form's intellect has helped in many situations. Ben first transformed into Grey Matter in "Washington B.C." when he saw that a gold Sumo Slammer card could be found in a box of cereal, and so searched through boxes of Sumo Slammer cereals. Although Ben rarely intentionally selects Grey Matter, he often finds himself in that form as a result of accidental transformations. Most of these situations occur when Ben intends on transforming into a large, powerful alien, making his change into Grey Matter all the more ironic. Humorously, while the Grey Matter form is able to understand almost any device, Ben does not consciously comprehend what he is doing and states as much a number of times.
 * Richard Steven Horvitz - Ben 10
 * Kari Wahlgren - Ben 10 (As Gwen in "Gwen 10")
 * Carlos Alazraqui - Ben 10: Race Against Time

Fourarms
Ben's preferred offensive form is Fourarms, a Tetramand (tetra meaning "four" in Greek, mand being "arms" in Latin) from the desert planet Khoros. Khoros epitomizes a dystopia, resulting in the strength-oriented Tetramands. Fourarms is a 12 ft four-armed, four-eyed powerhouse with armored skin and extremely dense musculature, making him unmatched in pure physical strength. His strength is such that he can create shockwaves simply by pounding the ground or clapping all four of his hands together, dubbed the "Big Smack", and his leg strength allows him to cross entire city blocks in a single jump. However, all the extra mass of his muscles and heavy skin makes Fourarms relatively slow, and his size likewise makes using things designed for smaller species difficult, especially when enlarging them. When under the effects of an illness, Fourarms's strength and stamina are somewhat lessened and he develops pungent hives in his armpits. Ben first transformed into Fourarms in "Washington B.C." when he needed to fight the giant woolly mammoth that Dr. Animo had reanimated. Fourarms reappeared in Ben 10: Ultimate Alien, wearing a much different costume and having an appearance reminiscent of a gladiator. He now has more authentic clothes of his original species (like Tini), with gold bracelets on his wrists and ankles, a ponytail, two gold sashes that cross over his trunk with the Ultimatrix symbol on the center of his chest, and green eyes instead of yellow. Fourarms is regained in "Video Games" in a fight with Ssserpent, and Ben was surprised because he did not know he was still there. The Ben's 10-year-old version of Fourarms made an appearance in the Ben 10: Ultimate Alien, in the episode "The Forge of Creation". With the exception of the Omnitrix badge on his shoulder changing from white to green, his appearance remained unchanged from the original series. Fourarms appears as a playable alien form in "Ben 10: Protector of Earth" and "Ben 10 Ultimate Alien: Cosmic Destruction" (as a PS3 exclusive).
 * Richard McGonagle - Ben 10
 * Michael Reisz - Ben 10 (As Kevin in "Kevin 11")
 * Charlie Schlatter - Ben 10 (As Kevin in "Framed")
 * Vanessa Marshall - Ben 10 (As Gwen in "Gwen 10")
 * Steven Blum - Ben 10 (As Baby Ben in "Don't Drink the Water")
 * Dee Bradley Baker - Ben 10: Ultimate Alien
 * John DiMaggio - Ben 10: Ultimate Alien (As the 10-year-old Ben in "The Forge of Creation")

Stinkfly
Stinkfly is a Lepidopterran from the swamp planet Lepidopterra (a play on lepidoptera, the scientific name for butterflies and moths). Another of forms more commonly used. Stinkfly is meant to be a combination of various Earth bugs (dragonflies, crickets, and preying mantises specifically). His primary ability is flight facilitated by the four thin wings on his back, which grant Stinkfly high mobility and speed. Stinkfly also possesses disproportionate strength, enough to carry people and objects heavier than himself. In "Don't Drink the Water", the child form of Stinkfly (Stinkyfly) was able to unleash a powerful herbicide gas by farting. Stinkfly's four eye stalks give him a wide range of vision from the sky, including the ability to look directly behind himself. Pollen ducts in his eyes and mouth allow Stinkfly to excrete high-pressure streams of liquids. The type of liquid can range from a flammable toxin to an immobilizing jelly. His razor-sharp tail and pincer-like legs can also be used in melee combat. Water negate Stinkfly's flight if it gets on his wings. In addition, while his body is fairly strong, his wings are not. A more minor inconvenience is Stinkfly's intense body odor (hence the name), which is a result of the oils he secretes to keep his joints moving. Ben first transformed into Stinkfly in "Washington B.C." when he had to save Gwen after she fell from the Washington Monument. The 10-year-old Ben's Stinkfly made an appearance in the Ben 10: Ultimate Alien episode "The Forge of Creation". His eye color changed from orange to green, His hands are green instead of black, his teeth are white instead of green, and he shot lasers from his eyes instead of liquid. His Omnitrix badge also changed from white to green.
 * Dee Bradley Baker - Ben 10 and Ben 10: Ultimate Alien (as 10 year old)
 * Charlie Schlatter - Ben 10 (As Kevin in "Framed")

Ripjaws
Ripjaws is a Piscciss Volann (from piscēs, the Latin word for fish) of the planet Piscciss, a 98% water-based world with solid matter only at its core, and the gravity is controlled by a gravity instrument, which holds all water and the beings on the planet, but Aggregor takes the instrument and shows that it was a piece of the Map of Infinity, and the anti-gravity projector of Goop now controls the gravity. Ripjaws shares a number of traits of Earth aquatic life-forms-namely alligators, eels, anglerfish, and sharks-combined into a single being. Naturally, his main ability is being able to breathe underwater and withstand a remarkable amount of pressure, his luminescent dangler allows him to see in the darkest of depths (or otherwise dark areas). He can swim at great speeds, and his sharp teeth and claws can pierce through almost anything. His lower jaw can unhinge to allow him to bite much larger objects. Though his tail hides a pair of legs for travel on land, Ripjaws is limited by his need to remain hydrated, dehydrating rapidly if left out of the water for even a few minutes, therefore, he is the one of the aliens less used in the series. Ben first transformed into Ripjaws in "The Krakken" in order to take the Krakken's eggs back from Jonah Melville. In Ben 10: Ultimate Alien, Ben regained Ripjaws in the Ultimatrix (likely from being on Ripjaw's home planet, Piscciss, the episode prior). The Ultimatrix symbol moves to his chest from his left-chest, he is more catfish-like, his eyes are green instead of purple and have pupils, he no longer has striped fins or clothes, the teeth are smaller and inside the mouth, he has green lips, thick eyebrows, bigger claws, and the phosphorescent light on his head also looks smaller. This looks different from the opening of Ben 10: Ultimate Alien. Ben used Ripjaws in the first time in the Ultimatrix in "Perplexhahedron", to escape from one of the traps of Perplexhahedron.
 * Fred Tatasciore - Ben 10

Upgrade
Upgrade is a Galvanic Mechomorph (mecho- meaning machine and -morph meaning shape) of the moon Galvan B, which orbits Galvan Prime. Upgrade is the only alien form in which Ben's voice does not change, aside from the more computerized tone behind it. The reason for this is revealed in the enhanced version of "Game Over"; Galvanic Mechomorphs cannot bond with living organisms, so Ben's transformation into Upgrade is incomplete. Upgrade is composed of nanotechnology, allowing him to reshape his body at will. This makes restraining or harming him difficult, as he can "melt" to avoid either and will quickly regenerate from any damage taken. Upgrade can also merge with other technology, earning his name by upgrading it far beyond its original design as long as he is merged with it. The size of the device is inconsequential. While merged with a device, Upgrade controls it as he would his own body. Even without a machine at hand, Upgrade can reconfigure his form around his eye to fire a positronic plasma beam from it, usually when angry, although Upgrade has rarely used it. Upgrade is also capable of forming simple constructs from plasma, such as spikes. Upgrade cannot possess biological creatures, and sentient or more powerful robots are harder for him to control, he is also weak against electricity. Upgrade's liquid-metal composition can also work against him, namely where electrical attacks are concerned. Furthermore, any sort of metal corrosive can upset Upgrade's delicate internal workings and wreak havoc on his systems. Ben first transformed into Upgrade in "Permanent Retirement" to stop some criminals who were robbing an ATM.
 * Tara Strong - Ben 10
 * Charlie Schlatter - Ben 10 (As Kevin in "Framed")
 * Paul Eiding - Ben 10 (As Grandpa Max in "Gwen 10")

Ghostfreak
Ghostfreak is an Ectonurite one of Ben's aliens who's DNA was taken from Zs'Skayr, the High Ecto-Lord of the Ectonurite homeworld of Anur Phaetos, who existed in the Omnitrix due to Ectonurites having the ability for their mind to exist in even in the smallest strand of their DNA. Ghostfreak's original appearance was similar to that of a ghost with only one eye and a black track along his skin but after freeing himself, he tore off the second skin to reveal his true horrifying form. He has the power to phase through matter and possess humans by going into them and controlling them. He also has telekinesis over beings he possesses and becomes far stronger if he's in complete darkness, which allows him to become even scarier in appearance and fire a powerful energy beam from his chest. In "Ghostfreaked Out", was reveled that Zs'Skayr's mind lay within the DNA sample of Ghostfreak, and he finally manages to force his way out of the Omnitrix, showing his true form, he is bigger, with a skull face turned up-side-down, sharp claws, and ghost tail with stripes. In Ben 10: Alien Force, Ghostfreak reappeared in "Ghost Town", when Ben absorbed Zs'Skayr, using the DNA absorb method of escaped Omnitrix aliens he used on "Vengeance of Vilgax", but with Ghostfreak's true form, though moment of transforming Ghostfreak quickly regained control of Ben, but with the help of Vilgax, Ben took control and transformed back.
 * Steven Blum - Ben 10
 * Jeff Bennett - Ben 10: Alien Force

Cannonbolt
Cannonbolt (A play on cannon ball) is an Arburian Pelarota (based on pelota, Spanish for "ball" and rota, a play on "rotation") from the planet Arburia. The information from the Bandai Alien Collection toy for Cannonbolt refers to his species as a Vulpinic Tortugan (tortuga is Spanish for "turtle") from the planet Vulpin, from which Wildmutt also originates. The Vulpinic Tortugans are Pellorotors that moved to Vulpin, then mutated due to the pollution and developed the ability to breathe fire. The Pellorotor home planet was destroyed by "The Great One" shortly before Ben discovers the form in "The Big Tick". Cannonbolt is the first new alien to appear on the Omnitrix, and eventually replaces Ghostfreak in the opening theme. Cannonbolt was originally meant to be one of the original ten aliens, but was replaced by Diamondhead in production. Cannonbolt is a hulking, broad-shouldered alien covered in natural armor plating. This armor can resist almost any attack, ranging from acids to lasers to extreme heat. By curling up into a ball, much like an armadillo or pillbug, Cannonbolt can encase himself in his armor, becoming virtually invulnerable. On Cannonbolt's planet curling up into a ball is a defence mechanism. He can then spin himself like a wheel, rolling into enemies at high speeds to attack. The drawback is that Cannonbolt quickly picks up inertia, which can make hitting more maneuverable targets difficult, as he cannot slow down quickly. In addition, Cannonbolt's speed and maneuverability is limited outside of his ball form, owing to his bulk and high center of gravity. The first time Ben used Cannonbolt was in "The Big Tick", but it was an accidental transformation, Ben wanted XLR8 to go to a fast-food restaurant and get some burgers for him and Gwen, the first intentional transformation was made in the same episode to try to stop "The Great One". In Ben 10: Alien Force, Cannonbolt was regrained by Azmuth after the Master Control of Omntrix was unlocked in "War of the Worlds". He has not changed a lot, he now has green eyes instead of yellow, has no longer a black stripe on his torso, with normal canine teeth, and his Omnitrix/Ultimatrix symbol moved from his forehead to his chest. He returns in Ultimate Alien, in the episode "Duped". "Revenge of the Swarm" is the first time that he attacks someone without using his ball form. As Ultimate Cannonbolt, his body is light metallic cyan with a darker shade of gray on his now metallic armor with cylindrical studs that turn into spikes when he goes into his ball form. In this state, he offers increased defense and more offensive capabilities therefore he can do/receive more damage than the normal, he also has increased speed, momentum and can bounce even higher. Ben used Ultimate Cannonbolt in "Too Hot to Handle" to hold Kevin and P'andor, with his armor that is made of some material that can contain radiation, allowing Kevin to seal P'andor back in his suit. Cannonbolt appears as a unlockble alien form in "Ben 10: Protector of Earth ", and "Ben 10 Alien force: Vilgax Attacks".
 * Fred Tatasciore - Ben 10
 * Vanessa Marshall - Ben 10 (As Gwen in Ben's body in "A Change of Face")
 * Dee Bradley Baker - Ben 10: Alien Force and Ben 10: Ultimate Alien

Wildvine
Wildvine is a Florauna (a combination of flora and fauna) from the planet Flors Verdance (a combination of flora and verdens, Latin for green). Wildvine is a plant-based alien with five vine-like legs, four-fingered claws, and venus flytrap-shaped flaps covering his head. Wildvine can grow to stretch his limbs great lengths or grow thorns to cause additional damage. He can also merge with other plants, and can burrow underground to conduct surprise attacks or travel quickly. Eight regrowable seeds on his back can be used as various types of explosives, both lethal and non-lethal. When exposed to cold, kept from sunlight, or deprived of a water source, however, Wildvine quickly withers up. Ben has never encountered any problems like these, likely due to the limited periods in which the form is used on the Omnitrix, although in episodes where he was used, he could still last without sunlight or water. Wildvine makes his first appearance in the episode "Camp Fear" to release himself and Max of the vines that hold them, and to face Mycelium. Ben's first intentional transformation into Wildvine was in "Tough Luck", when he used to the form escape a fall and to stop the Charmcaster's spell. Wildvine appears as a playable alien form in "Ben 10: Protector of Earth".
 * Jim Ward - Ben 10

Benwolf
Benwolf is a Loboan (as in Lobo, Spanish for wolf) from the Anur Transyl moon, Luna Lobo (literally translating from Spanish as "Wolf Moon"), scanned from the Yenaldooshi, which was actually an alien werewolf, in "Benwolf". Benwolf seems to be based on the Wolf Man, from various horror films of the mid-20th century, to keep with the "horror" element associated with Ghostfreak. Ben obtains this form after an alien of the same species scratched the Omnitrix in the episode "Benwolf", causing its DNA to be added into Ben's selection of aliens. According to the show's "popup edition", the result of Ben's battle leaves the Omnitrix half way between "Collection Mode" and "Active Mode", causing him to transform over the course of several hours instead of instantly as he normally does. Benwolf possesses super-strength and agility, and can send a green shock wave by peeling back his lupine snout. He can propel himself to the air by sending his shock wave on the ground. It is noted that he was never used again for unknown reasons. Benwolf is said to be affected by many other normal attacks and could be blinded by ultraviolet light, although there is no evidence showing this in the episode. Although Benwolf has color-blind vision, he never had a problem with it. Benwolf also finds it hard to resist his predatory instincts.
 * Tara Strong - Ben 10

Benmummy
Benmummy is a Thep Khufan (playing with the word Khufu, an Ancient Egypt pharaoh) from the desert planet Anur Khufos, scanned from a Thep Khufan who was a minion of Zs'Skayr (Ghostfreak) in "Under Wraps". Benmummy seems to be based on the Mummy, from various horror films of the mid-20th century, to keep with the "horror" element associated with Ghostfreak. The credits give the name "Benmummy", though Ben has yet to name it. Benmummy is covered in many bandages which he could control, allowing him to split themselves apart to dodge attacks and then reform to counterattack, and use them as tentacles. Benmummy can regenerate from any injury, including being torn into pieces, almost instantly and with no visible repercussions; the bandages make him extremely light, allowing him to be thrown even by human strength. Benmummy looks slightly different from the original, with his eyes and the gaps between his bandages glowing green instead of purple, having black bracers and greaves, as well as a smaller mask and the Omnitrix symbol on his left shoulder. Benmummy can speak, even though the original seems to be mute. Ben first uses him in "The Return" to fight off the Yenaldooshi, but that was an accidental transformation. When Ben first used the form, he had trouble figuring out how to control it. Ben quickly discovers how to stretch his bandages, but has not displayed knowledge of the advanced reshaping techniques yet; the first intentional transformation into Benmummy was made in the non-canon episode "Ken 10", when the future adult Ben Tennyson used it to take Ken out of the ventilation tube that he got stuck in when he tried to escape from his room as Grey Matter.
 * Richard Green - Ben 10

Benvicktor
Benvicktor is a Transylian (a play on the region of Transylvania, the setting for many monster movies) from the planet Anur Transyl, scanned from Doctor Vicktor in "The Return". Benvicktor seems to be based on the Frankenstein Monster, from various horror films of the mid-20th century, to keep with the "horror" element associated with Ghostfreak. Benvicktor has the ability to generate green electricity and blast it at others, able to walk on a metal surface with zero gravity because of this. He possesses super-strength and agility. The credits give the form's name as "Benvicktor", even though Ben himself has yet to name it. Benvicktor looks slightly different from Doctor Vicktor, as sports longer hair and a smaller left eye. Doctor Vicktor displays other powers, such as being intelligent and is able to connect himself to other devices to power up. Benvicktor was first used in "Be Afraid of the Dark" to face Ghostfreak in the space shuttle. He returns in the Ultimate Alien episode "Dr. Victor Returns".
 * Michael Dorn - Ben 10

Upchuck
Upchuck is a Gourmand (from the French word "gourmet," meaning "one who enjoys fine food" or "glutton") from the planet Peptos XI ("Peptos" being the Greek word for "cooked" or "digested" and the XI being the Roman numeral for eleven). Upchuck is a small alien with a very large appetite. He has four strong, adhesive tongues that can stretch to great lengths, allowing him to latch onto large objects and reel them in with relative ease. Upchuck's mouth and stomach stretch to facilitate the digestion of such objects. Upchuck possesses several acid-filled stomachs that can dissolve all forms of inorganic matter, meaning he cannot digest organic matter such as ordinary food. The items ingested are converted into explosive balls of liquids that can be expelled at will with great accuracy. He can also eat energy and rays, when he eats rays, he can shoot the ray just as it is fired. Upchuck also seems to have impressive stamina for his size, as he is able to take on the impact of a moving car as well as survive being thrown through a wall. An impediment to Upchuck is his small stature. Despite his appetite, Upchuck cannot seem to easily digest human food, as Ben realized when he tried to eat pizza, only to discover the alien form did not like the food, he remarks that he was not able to digest it because the acids in human food are not stable enough to digest, but in the episode where he fought a brought-to-life Mr. Smoothy (which was, oddly enough, actually filled with smoothy) he could drink the smoothy. This was due to either being able to now digest human food or Mr. Smoothie being digestible to gourmands. He is able to self destruct, probably after a continued amount of bad digestion. Upchuck also has a limit to how many big objects it can swallow. He is also slow when he eats a lot of things and becomes excessively fat, in his premiere episode The Visitor, when he finishes eating the mecha-robot; he rolls around due to his fatness. Otherwise, he is somewhat quick, considering his small size, but due to his body structure his speed is limited. This weakness is now gone in Alien Force. Upchuck first appears in the episode "The Visitor", in which Xylene (Grandpa Max's former alien girlfriend) enters a code into the Omnitrix to unlock the form, to destroy a Vilgax's drone. Like Cannobolt, Upchuck was regained by Azmuth from "War of the Worlds". In Ben 10: Alien Force and Ultimate Alien, Upchuck's appearance is slightly different from the original series, now the Omnitrix/Ultimatrix symbol was moved to his chest from his left hand, his color scheme was changed to browns and yellows, and his eyes were changed from white to green. Upchuck also did not use the four adhesive tongues that he possesses or used to possess. He returns in Ultimate Alien, episode "Duped". Upchuck appears as a playable alien form in the DS versions of and "Ben 10 Alien Force: Vilgax Attacks"
 * Dave Wittenberg - Ben 10
 * Dee Bradley Baker - Ben 10: Alien Force and Ben 10: Ultimate Alien

Ditto
Ditto is a Splixson (based on the word "split") from the Earth-like planet Hathor. Ditto is a humanoid child alien with the ability to clone himself without limit. Every clone operates independently, regardless of whether or not Ben wants them to, and is indistinguishable from the others. Though the clones are autonomous, they share each other's pain, and the death of one clone will cause the death of the rest, which negates the usefulness of making large numbers of clones, explaining the reasons why Ben rarely creates many clones of Ditto in the limited times he has appeared. The child-size Ditto is also no stronger nor faster than his size and build suggests. Ben activated Ditto accidentally in the episode "Divided We Stand", to fight against the seagull mutated by Dr. Animo. His first intentional Ditto transformation was in the same episode, when Ben wanted to have fun at the beach and turned into eight of them.
 * Rob Paulsen - Ben 10

Eye Guy
Eye Guy is an Opticoid (from the Greek word opticos, which means "something that you can see") from the planet Singhtra. He was introduced in the first alternate opening of "Ben 10: Secret of the Omnitrix", replacing Heatblast during the fight with Doctor Animo. How Eye Guy was obtained is never addressed. Eye Guy's upper-body is covered in eyes, hence the name, though he ironically has no eyes on his head, which consists of a mouth and a very large pair of bat-like ears. From these eyes, Eye Guy can fire numerous energy beams. The eyes can be merged to create different effects, such as three on his shoulder, which can form a freezing beam. By merging every eye into the large eye in his chest, he can fire his strongest energy blast. He can also scale walls. His only appearance in the TV series itself was in "Ben 10 vs. the Negative 10: Part 2", where Ben was attempting to prevent the Negative 10 from stealing the Sub-Energy.
 * Dee Bradley Baker - Ben 10

Way Big
Way Big is a To'kustar (from the Japanese term "tokusatsu", given Way Big's resemblance to characters from the Ultra Series), said to be from Galvan Prime, although they have been said to have no home planet, as they are created during cosmic storms. Way Big is Ben's tallest alien as of this time, standing at 200 feet (67 meters). This size grants him extraordinary strength and invulnerability to most attacks. He is also is capable of creating energy blasts, as seen being used against Gwen in "Absolute Power". Way Big is first introduced in "Ben 10: Secret of the Omnitrix" after Azmuth decides to remove the self-destruct mode of the Omnitrix. On the TV series, Way Big first appears in the non-canon episode "Ken 10" when the future adult Ben Tennyson used him against Kevin 11,000 when Kevin hurt his son Ken. Way Big, like Upchuck and Cannonbolt, returns in the second season finale of Ben 10: Alien Force after Azmuth unlocks the Omnitrix Master Control in "War of the Worlds". His eyes are now green instead of yellow, the spikes on his shoulders are gone, his face is different and the fins on his hips are gone. He also appeared in Ben 10: Ultimate Alien in the episode "Video Games". Way Big appears as a playable alien form in "Ben 10 Ultimate Alien: Cosmic Destruction".
 * Fred Tatasciore - Ben 10
 * Dee Bradley Baker - Ben 10: Alien Force and Ben 10: Ultimate Alien
 * Yuri Lowenthal - Ben 10 Ultimate Alien: Cosmic Destruction (As Albedo)

Future Aliens
In the episodes "Ben 10,000" and "Ken 10", a future version of Ben from an alternate Crosstime utilises three alien forms unused in the present day. Although the events of these episodes are arguably non-canon in the first series, these three aliens would later appear in the "Ben 10: Ultimate Alien" opening sequence, proving that they, at least, are canon. Five other aliens were mentioned in "Ken 10" (Atomix, Sandbox, Snakepit, Shellhead, and Toepick), although they are non-canon because they have not appeared yet in the sequel series.
 * In "Ben 10,000", Spitter (voiced by Dee Bradley Baker) is an alien used by the future adult Ben Tennyson in his fights with Doctor Animo and Vilgax. He is a large, blowfish-like alien with stubby legs that end in stumpy feet (similarly shaped like that of a rhinoceros' foot), a lizard-like tail, and short arms. Spitter has the ability to inflate himself and spit out a pressurized concentrated blast of slime. The slime is very slippery, can be acidic and has been shown to be highly conductive.
 * In "Ben 10,000", Buzzshock (voiced by Tara Strong) is one of the aliens used by the future adult Ben Tennyson in his fights with Doctor Animo. He has the ability to manipulate electricity and can fly.
 * In "Ben 10,000", Arcticguana (voiced by Tom Kane) is one of the aliens used by adult Ben Tennyson where he uses this form to freeze Vilgax in the river. Even though the adult Ben said he stopped naming his aliens, the younger Ben convinces him to name him Arcticguana. In "Ben 10,000 Returns," Ben 10,000 obtains Arcticguana's powers to use against Eon's ninjas. He is a blue iguana-like alien that can breathe freezing vapor.

Swampfire
Swampfire is a Methanosian from the planet Methanos (referring to methane). Swampfire is another plant alien with a fire-patterned head and root-like feet. He is described as a living swamp. He has superhuman strength, vast regenerative powers, the ability to control plant life through a type of flammable gas, and the ability to shoot fire from his palms, which can also be used to launch his body for flight. The fire is created by igniting methane naturally produced within his body, which causes him to constantly emit a very foul odor. He can also produce seeds that quickly grow into vines that he can control. His regenerative ability allows him to alter his own body, such as tunneling underground in vine form, growing his feet to root himself into the ground, heal the limbs of others, or passing through prison bars. However, Swampfire is more vulnerable than Heatblast because he can be frozen for periods of time, unlike Heatblast, who is completely invulnerable to cold. He appeared in pilot episode of Ben 10 Alien Force, in "Ben 10 Returns: Part 1" after the Omnitrix had reformatted. As Ultimate Swampfire, he is a tree-like version of himself with blue gooey shells containing an organic, blue-colored napalm kerosene gel-like solution, containing a highly flammable substance that Ultimate Swampfire uses to create fire bombs, nova blasts, and blue fire tornadoes. Although Ultimate Swampfire cannot regenerate himself, he is also tougher. Ben used Ultimate Swampfire on the first time in the Ben 10: Alien Force's series finale "The Final Battle: Part 2", to fight Vilgax, and he was the first ultimate form used by Ben. Swampfire appears as a playable alien form in "Ben 10: Alien Force The Game", "Ben 10 Alien Force: Vilgax Attacks", "Ben 10 Alien Force: The Rise of Hex", and "Ben 10 Ultimate Alien: Cosmic Destruction" with also Ultimate Swampfire.
 * Dee Bradley Baker - Ben 10: Alien Force and Ben 10: Ultimate Alien

Echo Echo
Echo Echo is a silicon-based life form known as a Sonorosian from the planet Sonorosia (from the word "sonoros" in Galician, meaning "sound"). He is a small white alien whose body is a living amplifier, a square appendage resembling an MP3 player behind his back with a port on it decorated with a binary digit situated like the number 10, and what looks like cassette tapes on his lower legs. He can scream at ultrasonic frequencies capable of overloading machinery and stopping projectiles in mid-flight. He also has the ability to duplicate himself like Ditto, but different in that the clones are not linked in any way and can revert even if all duplicates are not re-integrated, which splinters the original's personality. With these skills, Echo Echo can create a "Wall of Sound", where he and his clones can redirect projectiles back to their source by bouncing them off of strategically placed clones. He can also use echolocation, and can channel vibrations to enhance his power. He can also transmit sound waves through speakers. The first time he appeared was "Ben 10 Returns: Part 2" to fight the Forever Knights' dragon robot. As Ultimate Echo Echo, he is a blue, taller, and more robotic version of himself with green eyes and black lines on his body. In this state, Ultimate Echo Echo is unlike his regular form, he cannot duplicate himself anymore (As confirmed on the Cosmic Destruction site), but this limitation is well matched with incredible new abilities, can now shoot sonic screams and sonic waves from discs instead of from his mouth, these discs are on many parts of his body, that can be thrown and controlled, also he can fly with the projection of sound waves. Ben used Ultimate Echo Echo for the first time in "Map of Infinity" to fight the Necrofriggian Guardians, and to help Gwen and Kevin with the traps of the temple. Echo Echo appears as a playable alien form in "Ben 10: Alien Force The Game (Only on DS version), "Ben 10 Alien Force: Vilgax Attacks", "Ben 10 Alien Force: The Rise of Hex" and "Ben 10 Ultimate Alien: Cosmic Destruction" with also Ultimate Echo Echo.
 * Dee Bradley Baker - Ben 10: Alien Force and Ben 10: Ultimate Alien

Humungousaur
Humungousaur is a Vaxasaurian ("sauria" being a clade of lizards, while "vaxa" in Icelandic means "grow"), a humanoid dinosaur alien from the planet Terradino ("terra dino" means "dino land" in Italian). He is a four meter (12 foot) tall dinosaur-like alien. Humungousaur possesses great strength and a thick layer of skin that provides vast resistance to injury. Humungousaur also has the power to increase his own body size and mass, growing up to sixty feet in height (making him Ben's second largest alien right after Way Big). His strength increases as he grows, and his dinosaur features become more pronounced, growing Stegosaurus-like plates on his back, a crest from his forehead, and spikes on his tail. Recently Humungousaur has proven to be durable enough to survive in space for at least a few minutes. His first appearance is in "Ben 10 Returns: Part 2" when Ben fights a swarm of DNAliens. As Ultimate Humungousaur, he is larger (approximately 6 metres), green-skinned, armored version of himself with grey horns on his head, arms, chest and back. There is a spiked club at the end of his tail, similar to an Ankylosaurus, and his back is covered by a large, spiked shell. He is now capable of converting his hands into bio-Gatling guns that shoot kinetically unstable bone fragments as missiles. This form was first used by Albedo in "The Final Battle: Part 1" to fight Ben as Humungousaur, being the first Ultimate Form used in the Ultimatrix. Ben first uses him in the Ben 10: Ultimate Alien episode "Too Hot to Handle" to fight P'andor and his minions (Surgeon, Hammer and Buzz). Humungousaur appears as a playable alien form in "Ben 10: Alien Force The Game", "Ben 10 Alien Force: Vilgax Attacks", "Ben 10 Alien Force: The Rise of Hex" and "Ben 10 Ultimate Alien: Cosmic Destruction" with also Ultimate Humungousaur.
 * Dee Bradley Baker - Ben 10: Alien Force and Ben 10: Ultimate Alien

Jetray
Jetray is an Aerophibian (a play on "aero" for air and "amphibian") from the planet Aeropela. Jetray is a manta ray-like alien who has yellow horns extending from the center of the eyes and two wings which are attached to his arms. He is capable of flying and swimming at super-fast speeds, around 300 mph and over. Jetray is as fast as XLR8 being able to reach significant fractions of light speed. Jetray's ability is to shoot neuroshock blasts through his eyes and tail which are strong enough to carve through stone. He does not need oxygen to breathe, enabling him to easily travel through water and space. Jetray first appears in "Everybody Talks About the Weather" when Ben needed to chase after Alan Albright. Jetray appears as a playable alien form in "Ben 10: Alien Force The Game" (Only for Wii, PS2 and PSP versions), "Ben 10 Alien Force: Vilgax Attacks", and "Ben 10 Alien Force: The Rise of Hex".
 * Dee Bradley Baker - Ben 10: Alien Force and Ben 10: Ultimate Alien

Big Chill
Big Chill is a Necrofriggian ("necro", meaning death, and "frigid", meaning very cold) from the planet Kylmyys (the Finnish word for coldness). He is a ghost and moth-like alien, Big Chill's wings and antennae can fold up into a cloak of sorts, giving him the appearance of a phantom. He can become intangible, fly, has superhuman strength, despite his frail appearance, and can breathe freezing vapor. He can also freeze the objects it phases through at his discretion. He can also make ice beams from his hands, and control the flow of these beams. Big Chill is easily capable of withstanding extreme heat, at one point drinking molten metal directly from a massive smelting cauldron. Big Chill, like Jetray, does not need oxygen. Necrofriggians are also known to asexually reproduce, laying a vast number of eggs every 80 years. During its reproductive cycle, the Big Chill persona takes over Ben's body and eats metal objects, and causes him to act in a manner not unlike a pregnant female. Ben does not remember anything he does as Big Chill during the cycle. He first appears in "Kevin's Big Score" to chase down Kevin after he stole the Rustbucket. As Ultimate Big Chill, he is red-skinned version of himself with flame-like patterns at the ends of his wings, antennae and around his eyes. In this state, Ultimate Big Chill can now also create "ice flames", flames that turn to ice, and freeze faster than the normal, they are flames that consume the heat of whatever they touch, and use that energy to burn. He was first used in "Hit Em Where They Live", to fight Vulkanus and his Pickaxe Aliens army. Big Chill appears as a playable alien form in "Ben 10: Alien Force The Game" (Only for Wii, PS2 and PSP versions), "Ben 10 Alien Force: Vilgax Attacks", "Ben 10 Alien Force: The Rise of Hex" and "Ben 10 Ultimate Alien: Cosmic Destruction", with also Ultimate Big Chill.
 * Dee Bradley Baker - Ben 10: Alien Force and Ben 10: Ultimate Alien

Chromastone
Chromastone is a Crystalsapien (a combination of "crystal" and "sapien" which means intelligent being made of crystal), originally thought to be from the planet Mor'Otesi ("ultraviolet" in Turkish language). The planet does not exist, however. This means that the events of Ben 10 Alien Force: Vilgax Attacks are non-canon, and Mor'Otesi technically is a nonexistent planet. Chromastone is a super dense silicon life-form able to absorb energy like a conductor and channel it into laser blasts or less-intense natural light. He can also allow it to pass harmlessly through his body via refraction, or can be blasted back at the foe. Chromastone can seemingly produce blasts without having to absorb energy, though it may be due to absorption of radiant energy like sunlight, or streetlamps or just ambient energy. Chromastone also has the ability to fly. Chromastone first appears in "All That Glitters" to stop the zombified schoolgirls. During the episode "Vengeance of Vilgax: Part 2", Chromastone was seemingly destroyed by Vilgax, but the alien's remains reformed into Diamondhead. The reason for this is connected to the fact that only one Crystalsapien exists, who is Sugilite, the genetic donor for Chromastone. Sugilite hid himself until the time came for him to restore Petropia (which was shortly after Vilgax's destruction of the planet). It is believed that Chromastone (or more specifically Sugilite) is the guardian of the Petrosapiens, and that he was created as a backup system for Petropia in case the planet was destroyed. Although Chromastone becomes accessible again after the events of "The Secret of Chromastone", Ben did not use him until the pilot episode of Ben 10: Ultimate Alien, to fight Bivalvan, being very surprised that he still had access to the form, but when Chromastone was electrocuted, he had passed out, because he was not expecting it or is too weak to do so. He wasn't used again in the Ultimatrix until in the episode "The Creature From Beyond" to search for Lucabra. Chromastone appears as a playable alien form in "Ben 10: Alien Force The Game" (Only for DS version), "Ben 10 Alien Force: Vilgax Attacks", and "Ben 10 Alien Force: The Rise of Hex".
 * Dee Bradley Baker - Ben 10: Alien Force and Ben 10: Ultimate Alien

Brainstorm
Brainstorm is a Cerebrocrustacean (a play on "cerebrum" and "crustacean") from the planet Encephalonus IV (a play on "encepha-", a prefix referring to the brain). Brainstorm is a genius crustacean-like alien with the ability to control electrical energy, project force fields around him and others through thought and magnetic energy waves, accomplished by opening the exoskeleton plates on his skull. He also has the power to levitate, and create electricity from his pincers without needing to open his skull plates as well, and can also cause a storm just by thinking. In this form, Ben speaks with much greater diction and with a British accent. Also the species tends to be selfish which makes them forget how to do simple things as seen in "Vengeance of Vilgax" where Brainstorm forgot to capture a wild Spidermonkey due to its cocky attitude, they also tend to use large, scientific or intelligent terms that may not be understood by those they are talking to, Brainstorm's electro blasts can be grounded and a weak spot is at its brain, when struck he experiences excruciating and unbearable mental pain, which is probably why the species developed the casing. He was first seen in "Pier Pressure", to face Ship, but Brainstorm was an accidental transformation. All aliens in Ben 10: Alien Force and Ultimate Alien have the Omnitrix/Ultimatrix symbol on their chest except for Brainstorm, who has it in his cephalothorax. Brainstorm appears as a playable alien form in "Ben 10 Alien Force: Vilgax Attacks", and "Ben 10 Alien Force: The Rise of Hex".
 * Dee Bradley Baker - Ben 10: Alien Force and Ben 10: Ultimate Alien

Spidermonkey
Spidermonkey is an Arachnichimp (a play on arachnid and chimpanzee, Spidermonkey's name is also an obvious pun on spider monkey) from the planet Arahnascimmia (which is also called "Arachna", according to Simian and the Ben 10 Alien Force Complete Guidebook). As his name suggests, he is a six-limbed monkey-like alien, with four green eyes, hairy body, and a line coming out from his Omnitrix symbol to his back. He has superhuman agility and, like a spider, can stick to walls, spin webs that he can swing from or create spider web from his tail, although incredibly agile, he can get tangled by its own web. He first appears in "What Are Little Girls Made Of?" to face his grandma Verdona. As Ultimate Spidermonkey, he is a bulky gorilla with four spider legs sprouting from his back. In this state, Ultimate Spidermonkey is stronger and can spit webs from his mouth, which are very tough and is waterproof. He was first seen in the pilot episode of Ben 10 Ultimate Alien, to fight Bivalvan, being the 3rd Ultimate Transformation (or as Azmuth calls them, "geo orchidites") after Ultimate Humungasaur and Ultimate Swampfire. Spidermonkey appears as a playable alien form in "Ben 10: Alien Force The Game" (Only for Wii, PS2 and PSP versions), "Ben 10 Alien Force: Vilgax Attacks", "Ben 10 Alien Force: The Rise of Hex" and "Ben 10 Ultimate Alien: Cosmic Destruction" with Ultimate Spidermonkey.
 * Dee Bradley Baker - Ben 10: Alien Force and Ben 10: Ultimate Alien

Goop
Goop is a Polymorph (a word meaning "many shapes") from the planet Viscosia (a play on "viscosity"). He is a viscous life form, shape-shifting, self-regenerating green blob that weighs 200 pounds. Goop controls his slime through an artificial gravity generator, like a small UFO that has a button on it that turns him off. The gravity generator allows the slime to take any shape and levitate. However, if the ship and the slime are separated by even a short distance, the slime will become inert until the ship recollects it, as shown in the episode "Primus" when Ben gave Vilgax the Omnitrix and turned him into Goop except Ben turned off the gravity mode on the gravity generator. In "Deep" Goop used his anti-gravity projector to keep the Piscciss planet's gravity, and he kept his generator there, even when Ben turn to human form, but the Ultimatrix will generate another anti-gravity projector. He also said that the original species of Goop did not use a projector. Goop's slime can be made acidic, and the ship's edges have been shown to be sharp enough to cut through material such as Swampfire's body. Goop first appears in "The Gauntlet" when Ben battles a Techadon and also can extend it's size to bigger forms. Goop appears as a playable alien form in "Ben 10: Alien Force The Game" (Only for DS version), "Ben 10 Alien Force: Vilgax Attacks", and "Ben 10 Alien Force: The Rise of Hex".
 * Dee Bradley Baker - Ben 10: Alien Force and Ben 10: Ultimate Alien
 * James Remar - Ben 10: Alien Force (As Vilgax in "Primus")

Alien X
Ben Bellicus Serena Alien X is a Celestialsapien ("celestial" referring to a supernatural being and "sapien" meaning "wise" in Latin), native to their Forge of Creation, their birthplace, outside the known Universe. Though, some Celestialsapiens also live in the Milky Way. This type of alien has a black body resembling space with tiny white stars, black hands, green eyes, and three horns protruding from the head. Though Celestialsapiens are capable of warping reality at a whim, they are all usually in an inactive state of internal debate on how to manipulate time and space due to two conflicting personalities: Bellicus, the voice of rage and aggression, and Serena, the voice of love and compassion. Though the two are usually unable to agree on anything, they make an exception in the case of Paradox as they both detest him to the point of allowing him to exist only if he stayed far away from their kind. Alien X is the tenth alien that Ben becomes after his Omnitrix was reformated when he stops a dam that had burst in "X= Ben + 2", becoming a metaphysical medium for both Beliacus and Serena to settle their debates as their voice of reason while physically unable to move as Alien X. When none of his ideas worked, Ben gave them the idea to let him become a different alien to fight the Incursions. Since then, though he acknowledges Alien X as one of his most powerful aliens, Ben cannot afford the cost that comes with assuming the form. The reason being that unless he can get either persona on his side, Alien X would be frozen in place. After getting the Ultimatrix, Ben had a security protocol that lock on the Alien X option to ensure the form would not be used if the item fell into the wrong hands and that he would not accidentally turn into it. Gwen and Kevin have the keys that undo the protocol. Ben had this undone in order to get Bellicus and Serena to help him to find the Forge of Creation and stop Aggregor, which did not go well. Paradox ended up getting Ben out of his Alien X form after the boy's attempt to reason with the two personalities fails prior to them realizing Paradox's presence and were about to vaporize him upon a quick mutual agreement. In Ben 10: Ultimate Alien it appears Alien X has the ability to levitate. Alien X seems to have only one major weakness, that is if there is no majority supporting the action, Ben would be frozen in place. Since he would be frozen in space, his unique powers and abilities to warp time and reality could be easily absorbed by Darkstar or other Osmosians. Alien X is featured in the video game "Ben 10 Alien Force: Vilgax Attacks." He is first mentioned by Paradox during the invasion that now would not be a good time to use Alien X. When Psyphon steals the energy core from Ben in order for Vilgax to send Ben into the Null Void, Paradox appears telling Ben that now is the good time to use Alien X. When Ben becomes Alien X, he tells Bellicus and Serena that if they do not help him stop Vilgax, the Earth will be destroyed with them alongside it. Alien X manages to deflect the Null Void beam back at Vilgax and Psyphon sending them into the Null Void.
 * Yuri Lowenthal - Ben 10: Alien Force and Ben 10: Ultimate Alien
 * Kevin Conroy - Ben 10: Alien Force
 * Jeff Bennett - Ben 10 Alien Force: Vilgax Attacks and Ben 10: Ultimate Alien
 * Vicki Lewis - Ben 10: Alien Force
 * Tara Strong - Ben 10: Ultimate Alien

Lodestar
Lodestar (a play on lodestone, a magnetic iron ore) is a Biosovortian from the planet Attracta. Lodestar has a floating metal head which levitates between his shoulders, which are held in place magnetically, has crab like claws for hands just like the claws on his feet, have mainly black and yellow bodies which somewhat resemble a bee's body. He has the power to create magnetic fields, enabling him to repel, attract, emit magnetic pulses, and control metallic objects, and also use magnetism waves as attacks, he has an armored hull, very tough, but does not support an explosion, in the other hand, he can regenerate itself, and also he can make a shield and fly. Lodestar is introduced in the third season episode "Simple", though his hologram is seen at the end of "War of the Worlds" when the Omnitrix resets itself. Lodestar appears as a playable alien form in "Ben 10 Alien Force: The Rise of Hex".
 * Dee Bradley Baker - Ben 10: Alien Force and Ben 10: Ultimate Alien

Rath
Rath (a play on "wrath") is an Appoplexian (a play on "apoplexy", a part of the brain that deals with anger) from the planet Appoplexia. His appearance looks like a large, muscle-bound, humanoid tiger with no tail. However, unlike tigers who are known to be intelligent, patient and cunning creatures, Rath's species suffer from heightened aggression and decreased intelligence, having a need to fight anything that breathes, making Rath just as likely to attack or provoke his friends as well as his foes and as a result alters Ben's personality the most among his aliens, become easily distracted and difficult to stop once he starts fighting. Rath always refers to someone by using both their first and last names regardless of the situation and his mannerisms and speech are reminiscent of a professional wrestler. Rath has a tendency to say "Lemme tell ya somethin'!" followed by the full name of whoever he's talking to, and also refers to himself in the third person. However, Rath is more than able to back up his threats and is one of Ben's most powerful aliens, as his species is gifted with enough physical strength to easily lift objects far larger than him and pummeling most of Ben's enemies with ease, showing that his abilities to fight, depends better with your anger, like the Incredible Hulk. In addition, Rath has a retractable claw on his wrist that can generate shockwaves when driven into objects and Rath is also durable enough to survive for short periods in space and take a powerful laser cannon blast at point blank range without even flinching or reacting. His claws are sharp enough to cut a huge rock into two with ease. He was first introduced in "The Con of Rath" (a play on "Wrath of Khan") when the Tiffin of Luoda sets off a circuit in the Omnitrix. Rath appears as a playable alien form in "Ben 10 Ultimate Alien: Cosmic Destruction" (Only for Xbox 360 version).
 * John DiMaggio - Ben 10: Alien Force and Ben 10: Ultimate Alien
 * Jeff Bennett - Ben 10: Alien Force (As Azmuth in "Primus")
 * Dee Bradley Baker - Ben 10: Alien Force (As Albedo in "The Final Battle")

Nanomech
Nanomech is a miniature carbon-silicon-based life form, introduced in the film Ben 10: Alien Swarm. He is a Nanomechian from the hive planets. He has the ability to fly with his wings for added maneuverability, shoot energy bolts, and can also change the size of his body to adapt to any situation. Being a part of the chips' hive mind, however, renders him vulnerable to the Queen's link to the other chips; however, unlike the drones, he retains his individuality. It's worth noting he is drastically different than the source alien, which are insect-like, while Nanomech takes on a humanoid shape. He first appears in Ben 10: Ultimate Alien in "Video Games", with his appearance and voice changed; to be in a supposed video game he was going to appear in. Later in the same episode, he was used to tear apart the insides of Will Harangue's robot.
 * Alex Winter - Ben 10: Alien Swarm
 * Dee Bradley Baker - Ben 10: Ultimate Alien

Water Hazard
Water Hazard is an Orishan (A play on "oyster") from the planet Hydrosia (a pun on "hydro", referring to water). Water Hazard is a red, crustacean-like alien of bivalve origin, scanned from Bivalvan in the episode "Fame". He has a highly durable armored exoskeleton, can breathe underwater for a period of time, and is able to shoot pressurized water from his palms, as well as absorb ambient moisture from the air. His water jets are powerful enough to repel other creatures, and hurt human beings. Water Hazard first appeared in "Too Hot to Handle" to impersonate Bivalvan and tried to convince P'andor to leave Earth, but did not work because of the rivalry that existed between P'andor and Bivalvan. Water Hazard appears as a playable alien form in "Ben 10 Ultimate Alien: Cosmic Destruction". Some people mistake him as 'Ultimate Brainstorm' because he looks familiar with Brainstorm.
 * Dee Bradley Baker - Ben 10: Ultimate Alien

Ampfibian
Ampfibian is an Amperi (a play on "amp", a measuring unit for electricity) from the planet Amperia. Ampfibian is a blue jellyfish-like alien with four tentacle arms, scanned from Ra'ad. He has the ability to fire electrical bursts from his tentacles, drain electricity, turn intangible, read the electronic pulses that make up thought patterns, stretch all of his tentacles, and absorb and redirect energy beams. Ampfibian can also travel through air, water, and electronic currents by turning his body into electricity. Ampfibian, in "Fused", had a voice that sounds just like Ben's but it has the effect of being phase-shifted. In other episodes, however, it sounds like Ra'ad's. Though unintentionally first used in "Fused", where Ra'ad entered Ben's body during the DNA scan in a freak accident in an attempt to take the Ultimatrix offline to evade Aggregor, which explains that the first time, he had blue eyes because of Ra'ad. The first intentional use was in "Deep", to breathe under water on the planet Piscciss, where this time he has green eyes. Ampfibian appears as a playable alien form in "Ben 10 Ultimate Alien: Cosmic Destruction".
 * Yuri Lowenthal - Ben 10: Ultimate Alien (In"Fused")
 * Dee Bradley Baker - Ben 10: Ultimate Alien and Ben 10 Ultimate Alien: Cosmic Destruction

Armodrillo
Armodrillo is a Talpaedan (a play on "talpidae", a name for a family of mammals that includes subterranean animals such as moles) from the planet Terraexcava ("Terra", Latin for Earth, and "excava", a pun on "excavate"). Armodrillo is a yellow, bulky, robotic armadillo-looking alien with drills on his limbs, scanned from Andreas in "Andreas' Fault". His head looks similar to a Roman helmet and he has a long, grey tail. With the devices in his arms, Armodrillo has the ability to drill into the earth, or form jackhammers that cause tremors, shock waves and earthquakes. He is also very strong, being able to split the ground in half, and his tough skin protects him from injury. Ben first used Armodrillo in "Hero Time" in order to defeat the robots that Captain Nemesis released. Armodrillo appears as a playable alien form in "Ben 10 Ultimate Alien: Cosmic Destruction".
 * Dee Bradley Baker - Ben 10: Ultimate Alien

Terraspin
Terraspin (a pun on terrapin, a type of turtle, and "spin") is a Geochelone Aerio (a play on "Geochelone", a tortoise found in Africa, Asia, and the USA, and "Aerio" a play on air) from the planet Aldabra (a pun on Aldabra Atoll, an island found in the Aldabra Group in the Indian Ocean), whose occupants are a peaceful race mentioned to be immune to mana-based attacks. Terraspin is a turtle-like alien with holes in his chest, stumpy legs, and big flat arms who possesses retractable claws that can be used as fingers, scanned from Galapagus in "Escape From Aggregor". Terraspin has the ability to shrink into his shell and blow the wind out of the holes in its forward using his fins and propellers, allowing varied powers such as creating winds and spinning himself, being able to fly using these skills, also, as said before, his species is impervious to mana. Ben first used him in the episode "Reflected Glory" to battle a Forever Knight robot that was accidentally activated by Cash. Unlike other aliens, Terraspin demonstrates discouragement, especially when he pronounces his name. Terraspin appears as a playable alien form in "Ben 10 Ultimate Alien: Cosmic Destruction".
 * Dee Bradley Baker - Ben 10: Ultimate Alien

NRG
NRG (a play on the word energy) is a Prypiatosian-B (a play on Prypiat, a city that was evacuated due to a Chernobyl disaster in 1986) from the planet Nucleria (a pun on "nuclear"). NRG is a radioactive being encased within an oven-like invulnerable containment suit, scanned from P'andor in "Too Hot To Handle". When released, he is able to shoot energy beams and can create intense heat bad enough to create the intensity of a nuclear bomb. NRG is capable of becoming intangible, so he cannot be touched except by the material his armor is made of. His armor is so tough as it can only be broken with a sharp piece of Taedenite. Even trapped in the armor, he can still shoot energy beams through the holes of the display, and can generate intense heat at his hands. NRG can also withstand extreme heat and is very strong. Just like P'andor, NRG speaks with a Russian accent. The first time NRG was used was in "The Forge of the Creation", to stop the 10-year-old Ben as the original Heatblast, but that was an accidental transformation. The first intentional transformation was in "Absolute Power Part 1" to save Alan from Ultimate Kevin, and then to defeat Gwen to leave him to stop Kevin. NRG appears as a playable alien form in "Ben 10 Ultimate Alien: Cosmic Destruction".
 * Dee Bradley Baker - Ben 10: Ultimate Alien

Other Aliens
Some aliens have made brief appearances on Ultimate Alien, or will appear.
 * Fasttrack is a Citrakayah from the planet Chalybeas who made his first on-screen appearance in "Basic Training," though he was first used by Ben off-screen. His name was not revealed during the episode due to the fact that he was transformed into between commercials, but the writer of episode "Prisoner Number 775 is Missing" confirmed name, species, and home world. He has superspeed and possible superstrength, as he was able to lift both Magister Hulka and Tack, a fellow plumber-in-training. He has not yet had a speaking part, but in the upcoming Ben 10 racing game, Ben 10: Galactic Racing, voices of aliens and characters may be heard.
 * Clockwork is an alien Ben 10,000 used in "Ben 10,000 Returns" and has been confirmed by Bandai to appear in the fourth series. His physical appearance has yet to be shown as he was only used through Ben 10,000's Ultimate Ben, but a hologram showed a structure similar to NRG's with a sort of half circle with a concave center above his head, which is a sort of flat head also like NRG's. He also has a hole in his chest where an ultimatrix symbol should be.
 * Eatle is an alien Bandai also confirmed to be used by the fourth series. Nothing is known about him.
 * ChamAlien is a Merlinisapien (as confirmed by the Ultimatrix itself when first scanned) who was first seen at the end of "Prisoner #775 is Missing" after scanning him from Prisoner #775, another Merlinisapien; he was jokingly dubbed "Overkill" by Ben, but his name is confirmed to be ChamAlien. He has the ability to scale threw walls, the ability to use camouflage, and has grow a stinger on the tip of his tail.
 * Jury Rig is a new alien scheduled to appear sometime in Ben 10: Ultimate Alien according to Eugene Son.