Characters in the Metroid series

This is a list of notable fictional characters in Metroid, a series of video games developed by Nintendo.

Samus Aran
Samus Aran (サムス・アラン) is the bounty hunter protagonist of the series.

Chozo
The Chozo are a mysterious and sage-like species featured throughout the Metroid series. The origins and age of the Chozo race and civilization are unknown, but they were once spread across several planets in the Metroid universe. Lore entries in Metroid Prime suggest that the race may have traveled to a higher plane of existence as opposed to dying out. The Chozo were extremely technologically advanced, but took pride in their elaborate statuary. They also exchanged knowledge with other species, including the Luminoth of Aether, the Reptilicus of Bryyo, and the Elysians of Elysia (robots which the Chozo themselves built). Lore found in Metroid Prime 3 specifically mentions a fellowship of enlightened species that once existed between the Chozo, the Luminoth, the Reptilicus, and another race called the Ylla. While the former three have been expounded on in the series, the Ylla are only mentioned in this piece of lore and have yet to be seen. They were also responsible for breeding the Metroids. While in the Japanese versions of the games, the beings are only ever identified by the generic term chōjin-zoku (鳥人族), a misunderstanding during the localization process led to the mistaken adoption of the descriptor chōzō (鳥像), rendered "Chozo," in the English versions instead. In Super Metroid, some of the Chozo statues would rise up and attack Samus; these bosses are called Torizo, substituting the native Japanese word tori "bird" for the usual, Chinese-derived chō. In Metroid Prime, in later areas in game play, Chozo ghosts appear and attack Samus. Although originally allies, they have been maddened by the Phazon corruption of their planet, and can no longer distinguish friend from foe.

Galactic Federation
The Galactic Federation (銀河連邦) is the governing body of the galaxy formed by an alliance of alien species, often contracts Samus with difficult missions to complete, with the aim of eradicating the Space Pirates. Samus trained in the Federation's military before becoming a bounty hunter, leaving some time after a disagreement with her commanding officer, Adam Malkovich. The Galactic Federation's troopers also use powered armor, and their technology usually bears multiple versions of their symbol, a stylized cross-shape. Troopers are also given a basic repeating assault weapon, and in Metroid Prime 3, some are equipped with the Phazon Enhancement Device. The Galactic Federation serves the role as both Samus' greatest supporter/ally and (in more recent games like Other M & Fusion) a behind-the-scenes antagonist.

Kraid
Kraid (クレイド) is a gigantic dinosaur-like beast and a member of the Space Pirate's High Command. His most prominent feature is his grotesquely oversized belly. First appearing in the original Metroid, he is the first part of the mini-boss duo along with Ridley. In Super Metroid he appears in his giant form, two screens tall and almost a screen wide. Metroid: Zero Mission retconned his size and appearance, showing he did not grow between games. He was also slated to appear in Metroid Prime as a boss in the Phazon Mines, with a metal dome covering his head and blue Phazon veins on his belly, but was removed due to time constraints. Kraid also makes a guest appearance in the background of the Brinstar Depths stage in Super Smash Bros. Melee, slashing the stage, causing damage to anyone unfortunate enough to be in his way, and rotating the stage.

Metroids
The eponymous in-game Metroids (メトロイド) are large jellyfish-like creatures with quadripartite nuclei. They are capable of siphoning an undetectable life energy from any life form, generally causing the death of the victim in the process. This energy can also be siphoned from the Metroid in turn, allowing it to be used as a living power source. The original Metroid establishes that exposure to beta rays would cause them to multiply very quickly. Metroid II: Return of Samus established a five-stage life cycle in which those Metroids native to SR-388 go through two stages of ecdysis followed by two stages of mutation, thus maturing through five previously unknown forms: Alpha, Gamma, Zeta, Omega, and Queen. Metroid Prime introduced three new, Phazon-mutated forms: Hunter Metroids, Fission Metroids, and Metroid Prime itself. Metroid Prime 2: Echoes has a Phazon-mutated strain of Metroid, the Tallon Metroid. Instead of siphoning all of their power from victims, they can feed directly off Phazon. They are born as Infant Metroids from cocoons and mature into adulthood when exposed to Phazon. The game also introduces Dark Tallon Metroids, Tallon Metroids corrupted by the Ing. In Metroid Prime 3: Corruption, three new mutations of Metroid appear: Phazon Metroid, which is almost exactly like a common Metroid, except that it is capable of phasing in and out of local timespace; Hopping Metroid, which cannot hover, phase out of local timespace, or drain energy, but can fight using its claws as melee weapons and armor for defense; and the Metroid Hatcher, a boss which can float and spawn Phazon Metroids, but cannot phase out of local timespace. It is believed that the Tallon Metroids (and their mutation) and Phazon Metroids (and their mutations) died out after the destruction of Phaze, due to their dependacy for Phazon.

Though Metroids are dangerous animals, they are presumably not intrinsically sinister or evil, but act only on instinct (however due to their abilities they are viewed as potential bio-weapons by the Space Pirates & the Galactic Federation). At the end of the second game in the series, Samus spares a baby Metroid, which imprints on her, seeing her as its parent. This Metroid later reappears in the sequel Super Metroid, where Samus delivers it to scientists on the Ceres Research station who plan on finding a way of using its energy absorbing properties for good intentions. The Metroid larva is soon stolen by Ridley, who takes it to Zebes where it is exposed to beta rays and multiplied, causing it to grow abnormally large, becoming the eponymous Super Metroid. Samus later encounters it in Tourian where it attempts to drain her energy, before recognizing her as it's mother and fleeing. It later reappears in time to save Samus from the rebuilt Mother brain by draining her energy and reviving a wounded Samus. Mother Brain revitalizes however, and kills it shortly afterwards.

In Metroid: Other M, on the space station called the "Bottle Ship", Samus discovers the space station is an illegal bio-weapons research facility. While investigating in Sector 2, Samus finds the frozen carcass of a Gigafraug that shows sign of Metroid predation, however she dismisses this notion as Sector 3 is a sub-zero environment (which is lethal to Metroids) and the last of the Metroids died on Zebes. However she eventually discovers that the Galactic Federation was planning to use Metroids cloned from the DNA remnants of the Super Metroid on her suit as bio-weapons. These Metroids had been genetically modified to be resistant to freezing, making them nearly indestructible. Samus later faces an un-modified Metroid Queen, whom she kills with a power bomb. The un-freezable Metroids are apparently wiped out in an explosion caused by Samus's former commanding officer.

In Metroid Fusion, Samus is injected with DNA from the infant Metroid recovered from the Ceres Space station in order to save her from being killed by the X parasite (giving her the ability to freely absorb X, but also their weakness to extreme cold), effectively making Samus the last of the Metroid. It is also revealed that the Galactic Federation was breeding Metroids in the Restricted Laboratory in B.S.L. (most of these were killed by one of the SA-X, resulting in the lab's ejection and destruction). An Omega Metroid appears as the final boss (having escaped the Restricted Lab), during B.S.L.'s collision course with SR388. According to Metroid Fusion's instruction manual, the name "Metroid" is a Chozo word meaning "Ultimate Warrior" and it is assumed that the Chozo created the Metroids to keep the X parasites of SR388 in check, resulting in the Metroid's becoming the top predators of SR388 (Samus' extermination of the Metroids on SR388 resulted in the re-emergence of the X on the planet). In Super Smash Bros. Brawl, a Metroid appears as a character that can be summoned through an Assist Trophy. Like in the Metroid games, it will attack by attaching itself to a character's head and sucking his/her life.

Metroid Prime/Dark Samus
Metroid Prime and it's alternate form Dark Samus is the main antagonist of the Prime subseries. It is a strange, black-carapaced, red-eyed creature with a humanoid face within its shell and the ability to control and horribly mutate anything it attaches to. Metroid Prime appears in Metroid Prime as the final boss, and after its defeat, reforms itself as Dark Samus, a black-colored doppelgänger of Samus, by stealing her "Phazon Suit". Metroid Prime appeared in Tallon IV shortly after the impact of the Leviathan, a living Phazon meteor, and fused with a Metroid unfortunate enough to cross its path. It caused severe damage to the Chozo colony before the Artifact Temple was built to contain Metroid Prime inside the impact crater of the Leviathan. According to the NTSC version of Metroid Prime, Space Pirate miners eventually discovered the creature, eventually dubbing him "Metroid Prime", and after containing him with security units and drones brought to their laboratories to perform experiments. Metroid Prime eventually broke free, and managed to assimilate several weapons and defense systems from fallen security units before going back to the impact crater (the PAL version denies this, with the Pirate Logs only stating the Pirates picked up life signals coming from within the Artifact Temple). After Samus gets all artifacts, she is able to enter the impact crater and fight Metroid Prime. After its defeat, the creature takes Samus' Phazon Suit to reconstruct itself into a body similar to Samus, the being called "Dark Samus". In Metroid Prime 2: Echoes, Dark Samus arrives in Aether chasing the planet's Phazon. Shortly after, Samus arrives and encounters Dark Samus many times, eventually defeating her as Dark Aether was destroyed - but a post-credits scene shows Dark Samus reforming herself in deep space. Metroid Prime 3: Corruption shows a team of Space Pirates returned to Aether to pick up Phazon, and eventually found Dark Samus, who killed a third of the Pirates and brainwashed the rest to be their leader. After discovering Phaaze, Dark Samus begins her mission to spread Phazon across the universe - one of the planets hit was the Pirate Homeworld, in order to turn the rest of the Space Pirates into followers of Dark Samus. In an attack to the Galactic Federation vessel G.F.S. Valhalla, Dark Samus steals a supercomputer, the Aurora Unit 313, and corrupts Samus and other bounty hunters with Phazon. After Samus destroys the Leviathans of four planets, she goes to Phaaze, where she finally defeats Dark Samus, who then merges itself with the Aurora Unit in a last-ditch effort to defeat Samus. After the Aurora Unit is destroyed, Phaaze explodes, and all Phazon in the galaxy is rendered inert.

IGN listed Dark Samus as the 88th best video game villain.

Mother Brain
Mother Brain (マザーブレイン) is a recurring game boss in the series. Its exact status has always been unclear, as it has been referred to as the general of the Space Pirates, a supercomputer that operates the Space Pirate-occupied world of Zebes, or a councillor of the Chozo. Mother Brain is depicted as a very large brain with cybernetic spikes and a single eye; usually contained in a glass tube which Samus must break to attack it. In Super Metroid, Mother Brain also rises from the floor with a grotesque body after her tank is destroyed. Samus seemingly destroys Mother Brain in the original Metroid, but again confronts it in Super Metroid; in this game, Samus is almost defeated, but the baby Metroid intervenes, and Samus once again defeats Mother Brain. It was revealed in Metroid Prime 3 that the Galactic Federation had constructed biomechanical supercomputers called Auroras, and that there were plans for a "Future Aurora Complex", which appears to be the Mother Brain depicted in Super Metroid. In the first cutscene for Metroid: Other M, the scene of Mother Brain destroying the baby Metroid is reenacted in an FMV cutscene, and one of the antagonists, MB, is an android housing an AI based off of Mother Brain.

Ridley
Ridley (リドリー) is a recurring antagonist of Samus Aran, an intelligent and sadisticdragon-like extraterrestrial that despite being killed multiple times by her, is always revived by the Space Pirates (or accidentally by the Galactic Federation in Metroid:Other M) using cloning or robotics. Other than Samus and the titular Metroids, Ridley is the only character that has appeared consistently throughout most of the games in the Metroid series (the exceptions being Metroid II for the Game Boy, Metroid Prime 2: Echoes for the GameCube, and Metroid Prime Hunters for the Nintendo DS).

Space Pirates
A hostile group known as Space Pirates (スペースパイレーツ) or Zebesians, serve as the antagonists of the Metroid series. They are a group of "interstellar nomads" resembling humanoid reptiles, insects or crustaceans, who plunder colonies and ships and exist in an insect-like hive society. Considering their appearannce throughout the series, especially the Prime Trilogy, they could be considered arthropodian-like reptiles. A single Pirate may have many biological differences between individuals of their own species, most likely because of their willingness to perform self-experimentation and mutation. Important leaders include Ridley, the Space Pirate commander, Mother Brain, the biomechanical defense of Zebes controlled by the Space Pirates, and Kraid, a recurring boss. The organization also includes a winged, mantis-like species, the Ki Hunters. The Space Pirates are interested in Metroid research, especially in using Metroids for energy generation, as soldiers, and for experimentation – their Phazon experiments produced all the Metroid variants seen in the Prime games with the exception of Metroid Prime itself. The organization is destroyed during the climax of Super Metroid, however a group within the Galactic Federation itself resurrects the Space Pirates (along with Ridley and the Metroids) to be used as bio-weapons (explaining their continued presence in Other M & Fusion).

Galactic Federation (Bio-Weapons Research Projects)
A small group within the Federation government was responsible for the events in Metroid: Other M and were a behind-the-scenes antagonist in Metroid Fusion. Secretly, this unnamed group within the Federation planned to breed Metroids and other creatures, like the Zebesians, to be used as bio-weapons, employing various methods to keep their activities a secret from the rest of galactic society. In Other M, they are revealed to have used genetic remnants of the baby Metroid obtained off Samus' powersuit after her mission on Zebes to genetically engineer a new breed of Metroid immune to the effect of cold temperatures. However, this project was foiled by the accidental cloning of Ridley and the rebellion of MB, the Mother Brain-like android created to control the Metroids. This leads to the interference of Adam Malkovich's team of soldiers and Samus. However, one of their operatives (called "The Deleter" by Samus) inflitrates Adam's squad to remove any evidence of the project. The presence of Samus derails the Deleter's mission, though he does manage to kill several members of Adam's squad. The actions of Samus and Adam's heroic sacrifice put an end to their bio-weapons research on the Bottle Ship, but their secret bio-weapons research and Metroid breeding program continues on the B.S.L. research station until it is overrun by the X parasites. In Fusion, Samus discovers the continued bio-weapons research and learns that they foolishly plan to capture the X parasites and the SA-X for the bio-weapons research, and crashes the station into the planet SR388 with the help of her ship's AI, which was based off of Adam Malkovich.

It is also believed that they are also responsible for the creation the powersuit, weapons, and ship stolen by the Federation-hating bounty hunter, Sylux from Metroid Prime Hunters.

Nightmare
Nightmare is gravity-controlling, monster cyborg created by the Galactic Federation's secret bio-weapons project, Samus encounters in Metroid: Other M and Fusion. Its main power is gravity manipulation and its main weak points are its tail and face (which is protected by a metal mask). Samus fights Nightmare twice (first masked and second unmasked) in Other M. In Fusion, an X parasite infects the Nightmare contained in Sector 5-ARC. It escapes and destroys ARC's data room, Samus confronts Nightmare-X, defeating and absorbing its Core-X, obtaining the Gravity Suit upgrade. The Nightmare has the distinction of being among the few boss characters to have been originally created by the Galactic Federation scientists (along with the B.O.X. Security Robot).

MB/Melissa Bergman
MB was created by the scientists of the Bottle Ship as a copy of the original Mother Brain in order to control the Metroids, Zebesians and Space Pirates that were being mass produced in Sector Zero of said starship. Originally, MB was only a computer software, but due to its inability to interact personally with the Metroids, the scientists decided to give her an artificial human body, so as to have her bond in a more organic way with the Metroids, mimicking Samus' mother-son-like relationship with the baby. Soon, MB, now named Melissa by her "adoptive mother" Doctor Madeline Bergman, gained a consciousness of her own just like the original Mother Brain once did, so her coworkers decided this was too dangerous and that she had to be shut down; something Madeline Bergman initially opposed to but ultimately accepted when faced with the dangers of keeping her active. The heavy trauma of having her mother rejecting her safety and finding out that the Galactic Federation actually created her for military purposes caused a meltdown in her mind and she decided to take judgement on humanity for their misdeeds, forcing the Bottle Ship in a collisional course against Norion. Melissa was confronted by both Samus Aran and Madeline Bergman at MV room after her Queen Metroid had been killed. Although both of them tried to persuade her, she did not listen and tried to kill Madeline, only to get shot down by the Galactic Federation and frozen by her own mother.