In the game, Necrons advantages include their devastating Gauss weapons, powerful and versatile Wargear, and their ability to self-repair. Their biggest weaknesses is their low number of unit types and high points cost. If a Necron army is reduced to 25% of its original strength (determined by remaining models in play), the remaining forces "phase out", and the opposing player(s) win instantly.
- There are currently four remaining C'tan in the 40K universe: The Outsider, The Void Dragon, The Nightbringer and The Deceiver. Of these only The Nightbringer and The Deceiver have been given rules and significant background. While The Deceiver is the weakest of the C'tan, he has been the most active and has earned his name. He pits all the other races against each other both to weaken them and for his own amusement. On the battlefield, he has various abilities which target enemy units' morale and leadership. The Nightbringer is (literally) death incarnate in the 40K universe, and is considered to be the most dangerous of the C'tan, having implanted himself as the personification of death in every species' racial memory, with the Krork (as the Orks were known millions of years ago) as the only exception. On the battlefield, he excels in close combat. The Adeptus Mechanicus believe that their Machine God is an aspect of the Emperor of Mankind, but some (both real-world gamers and individuals within the Warhammer 40,000 universe) postulate that it is actually the Dragon. Some evidence suggests that the Mechanicum worshiped something "far darker" before Mars' reunification with the Imperium. There is currently very little information about the Outsider, except that it was driven insane when it was tricked by the Deceiver into consuming its brethren during the War in Heaven. Its current whereabouts are unknown.
- Necron Lords are the commanders of Necron forces, chosen due to being one of the few Necrons to retain sentience and are currently the only choice HQ available. They are formidable foes on the battlefield, being quite adept with both ranged and close combat weaponry, although their main purpose is to enhance other nearby Necrons. Due to their special position as "leaders" in the Necron forces, they are often equipped with special gear. This gear can be used to either increase the effectiveness of other Necrons around the Lord, such as augmenting their healing factor, while other gear carried can increase the Lord's survivability or his prowess in battle. Necron Lords are also some of the few Necrons who keep pieces of memory remaining from their previous lives. Necron Lords are ranked in staged levels of importance, ranging from strike force level bronze lords, to platinum-level overlords. some necron lords carry resurrection orbs into battle. these devices have the power to bring destroyed necrons, back into the heat of battle.
- Flayed Ones are Necrons who retained their minds after transferred to their metal bodies, and have been driven insane by the endless solitude in the tombs. Enemy fighters lose their nerve by just looking at the Flayed Ones. They are quite capable melee fighters, with claws and blades that can flay a man alive in seconds. Flayed Ones also frequently serve as scouts and infiltrators, as they are capable of being teleported in individual squads to almost anywhere on the battlefield. They can sneak ahead of the main Necron force or even bury themselves in the ground to come out anywhere near other necron units. They frequently adorn themselves with the bloody skin of their victims in a horrible parody of the living. In such a state, they are a terrifying sight to behold. They can be upgraded with disruption fields which warp reality around their numerous claws. In the novel "Hellforged" it was shown that they are capable of folding their bodies in such a way as to hide themselves inside human corpses, although the corpses were in an advanced state of decay (and one would assume, somewhat bloated) at the time. In the same novel there was also an account of a Flayed One which was able to infiltrate a fortress (that was under attack at the time) by pretending to be a fatally injured soldier, in order to open a "back door" and allow the other Necrons access.
- Pariahs represent the true horror of a Necron-ruled galaxy. They are created by fusing Necron technology with human victims who bear the "Pariah gene" (an incredibly rare and unusual genetic defect which gives the bearer a negative warp presence). Each Pariah is a formidable warrior, and wields a deadly warscythe. They radiate an unnatural aura that severely unnerves their enemies, especially psykers. Interestingly, since Pariahs are partly human, they are currently unable to self-repair, unlike other Necrons.
- Within the Imperium, Humans bearing the Pariah gene are also known as Blanks, Nulls, or Untouchables. Some (if they are strong enough) become Culexus Assassins, who are used by the Imperium to combat enemy psykers, while others are generally found in an Inquisitor's retinue. It is possible that it was the C'tan who originally put the "Pariah Gene" in humanity's gene pool and have merely been waiting for the proper time to make use of it.
- The pahriah units are current no longer mentioned or used in the up-to-date Necron Codex.
- Necron Warriors are the backbone of the Necron army as they are currently the only troops choice available. They provide strong fire support with their Gauss Flayers, while their high toughness and strong armor make them extremely resilient. Despite being the Necron's basic troops, their Gauss weaponry allows them to take on many stronger opponents that they would not normally be able to harm, including vehicles. they are skeletal in appearance and are made from living metal which has the ability to repair itself, so even the most heavily damaged warriors can quickly return to battle. (In the desktop game this is represented by the "we'll be back roll".)
- Those favored Necrontyr who were among the first to give up their flesh and embrace the metal were rewarded by being Immortals. They are more durable, heavy variants of the Warrior and they wield Gauss Blasters, which are a more powerful version of the Gauss flayer wielded by the Warriors.
- In Warhammer 40,000: Dawn of War: Dark Crusade, they are described as dealing excellent damage to vehicles and normal damage to other unit types; for game mechanics reasons, units in Dark Crusade tend to be specialized against particular unit types.
- In the revised version of the Necrons codex, they can swap their Coil blasters for Tesla Discruptors.
- Destroyers are Necron Warriors (specifically Immortals) fused to fast and agile hover-platforms. Equipped with Gauss Cannons and sophisticated targeting systems which enable them to fire while moving. Destroyers are ideal for hit-and-run attacks or disrupting enemy flanks. Destroyers are usually used against enemy troops instead of enemy vehicles, and Necron Lords can be upgraded to be destroyer lords.
- Wraiths are one of the more sophisticated Necron units. They lack legs or a lower body (except for the spinal cord) and hover over the battlefield, moving at supernatural speeds. They are fearsome close combat warriors, and they can phase in and out of reality during their flight, becoming ghostly figures (thus the name wraith). This phase shift ability allows them to avoid being slowed when moving through obstructions or even to avoid damage. It has been suggested that Wraiths were murderers or psychopaths before their enslavement. They are armed with several vicious surgical tools on the end of their spinal cord. It is speculated that they can turn anti-psykers into necron pariahs.
- Countless small, beetle-like robots called Scarabs often appear on the battlefield; these clouds of Scarabs are termed Scarab Swarms by their opponents. These swarms rely on sheer numbers and are difficult to destroy. They are useful for disrupting enemies who are caught unaware, and for tying up fast and/or tough opponents. Tomb Spyders are capable of mid-game production of such scarabs, though at the risk of damaging the Spyder.
- Monoliths are massive weapons platforms that the Necrons bring into battle. Shaped like pyramids, these have the power to rip even the most powerful Imperial tanks to shreds, with one huge Gauss crystal-powered Particle Whip weapon on the top and several Gauss Flux Arc projectors on each of the corners, it also has a portal which can teleport Warrior squads to the battlefield. It can also use its portal to augment the Necrons self-repair capabilities.
- Tomb Spyders are large, spider-like robots that slowly hover over the battlefield, which are normally tasked with maintaining the Necron tomb complexes. On the battlefield they make resilient fighters who have limited ability to augment the healing factor of the "living metal" on nearby Necrons. They also can use their internal systems to manufacture Scarabs in the midst of a battle at the risk of injury to themselves. They can be equipped with a particle projector which is as comparable to the Necron Lord's Staff of Light, but they will lose some melee proficiency if equipped with one.
- The Heavy Destroyer is a more powerful version of the Destroyer, so it moves, shoots and has the same profile as the Destroyer. A Heavy Destroyer is armed with the Heavy Gauss Cannon which is useful for destroying foes with heavy armor (vehicles mainly).
<ref>tag; no text was provided for refs named