The Necrons

the Necrons are a mysterious robot-like race that have lay dormant and largely unknown by the other races of the universe for 60 million years, and are reemerging in the distant future of the Warhammer 40k universe. The Necrons have become known and feared for their ability to absorb large amounts of physical punishment, as well as their enigmatic, yet powerful, weapons and technology. Necrons are the most advanced race in the Warhammer 40k universe.

Necron Units
In the game, Necrons are powerful due to their devastating Gauss weapons and other powerful Wargear, Such as Warscythes, The Staff of Light, and other weapons as well as their ability to self-repair. Their biggest weaknesses are their low number of unit types and high points cost, not to mention the fact that they vanish if three quarters of their force are defeated.

Necron Destroyers
Destroyers are Immortals fused to fast and agile hovercraft 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. They also come in a Heavy Destroyer variant, which is armed with the more powerful Heavy Gauss Cannon, useful for destroying foes with the heaviest armour.

Necron Flayed Ones
Flayed Ones are Necrons who retain some of their original consciousness and have been driven mad by their ageless imprisonment. They are quite capable melee fighters, with claws and blades that can flay a man alive in seconds. They usually adorn themselves with still wet pieces of skin and hide from their latest victims. In such a state, they are a terrifying sight to behold, so much that sometimes enemy fighters lose their nerve by just looking at them. Flayed Ones also frequently act in a manner similar to scouts, sneaking ahead of the main Necron force or even burying themselves in the ground, and use either method to gain the element of surprise during a battle.

Necron Immortals
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, calibrated for maximum effectiveness against infantry. However, being armed with gauss weapons, Immortals are fully capable of taking down vehicles. One exception is that on the game "Warhammer 40,000: Dawn of War: Dark Crusade" they are described as being best against vehicles.

Necron Lord
Necron Lords are the commanders of Necron forces, chosen due to being one of the few Necrons to retain sentience. They are formidable foes on the battlefield, being quite adept with both ranged and close combat weaponry. Due to their special position as "leaders" in the Necron forces, they are often equipped with special gear. This gear often increases the effectiveness of other Necrons around the Lord, such as augmenting their healing factor, or allowing them to teleport to crucial points in a battle; 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.
The Necron Destroyer Lord is the upgraded version of the Necron Lord, the Lord's torso is attached to the body of a necron destroyer.

Necron Warriors
Necron Warriors are the backbone of the Necron army. They are numerous and provide strong fire support with their Gauss Flayers. Their "living metal" bodies allow them to sustain massive damage and continue functioning.

Necron Wraiths
Wraiths are one of the more sophisticated Necron units. They lack legs or a 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 during their flight, becoming ghostly figures (hence the name wraith). This phase shift ability allows them to move through solid objects or even to avoid damage. It has been suggested that Wraiths were murderers or psychopaths before their steel imprisonment.

Pariahs
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" (a rare and unusual genetic defect which causes the bearer to be soulless). 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 unable to self-repair, as do other Necrons.
Within the Imperium, Humans bearing the Pariah gene are also known as "Pariahs", but are also referred to as "Untouchables". Some become Culexus Assassins, who are used by the Imperium to combat enemy psykers. It is unknown whether the C'tan somehow control this temple or intend to do so in the future, for all its members are a product of their plans. It was the C'tan who originally put the Pariah gene in humanity, waiting for it to evolve to the point where they could use it to make Pariahs.

Scarab Swarms
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 to make themselves difficult to destroy, and are useful for disrupting enemies who are caught unaware. They can be upgraded with "disruption fields" which warp reality around their numerous claws. Large numbers of Scarab Swarms upgraded with "disruption fields" can tear apart even the most heavily armoured vehicles under a hailstorm of attacks.

Tomb Spyders
Tomb Spyders are large, spider-like robots which are normally tasked with maintaining the Necron tomb complexes. They sometimes appear on the battlefield, where 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 battleanced race in the Warhammer 40k universe.