The Necrons are a mysterious race of skeletal warriors that have lain dormant in their stasis-tombs for millions of years. They are ancient beyond reckoning, pre-dating even the Eldar. At long last however, they are beginning to awaken, for the galaxy is ripe for the greatest harvest since the demise of the Old Ones.
The Necrons' story is one of ancient betrayal. Aeons ago, the Necrontyr race clung to their short lives in fear of oblivion at the hands of their massive and ravaging star. They pushed the limits of science in an effort to lengthen their lives, but to no avail. In their desperation, the looked to their science and discovered ethereal beings feeding on the energies of whole stars. They named these beings the star gods, or C'tan. The C'tan offered the Necrontyr people immortality, but only at a terrible price. We will never know if the Necrontyr knew this price, but their race was completely purged and transferred into new metal bodies.
The C'tan are enormous energy beings who were given physical embodiments by the Necrontyr. They encased the C'tan inside vast lumps of their living metal, the same material they used in their space faring ships. The metal mutated into the shape desired by the personality of the being inside. The Night Bringer was forged into a dark figure with a large cloak, adding to the fear it already inspires, and the Deceiver was formed into a wily shape. Originally there were a large number of C'tan, but due to the machinations of the Deceiver, this number reduced to four, The Night Bringer, The Deceiver, The Dragon and The Outsider.
The Necrontyr accepted the C'tan's offer and their life essence was encased in living metal bodies. What they did not know was that the process dulled their minds and senses until they became slaves of the C'tan. The C'tan needed warrior-slaves to harvest the lifeforms of the galaxy so the star gods could feast on souls, and their new Necrons served this purpose very well.
The Necrons burst into the Old Ones strongest fortresses and destroyed their magics and technology. The Old Ones were forced to seed planets with life to help fight the C'tan, including the Eldar and Krork. These races had the ability to use the warp to defend themselves. Gradually, the Old Ones were forced back by the relentless push of the C'tan and billions of souls were harvested for the Star Gods. The C'tan had been working on a plan to cripple the Old Ones, and eventually it came to fruition. They burst into and destroyed the webways discovered by the Old Ones. Without these portals, the Old Ones were unable to move troops throughout the galaxy. With the new races using so much warp power for the purposes of killing, the benign creatures in the warp mutated into the evil creatures they are today. Then the Enslavers came, and forced the Necrons back with their psychic powers. The 4 remaining C'tan went into stasis to avoid the Enslavers and allow the galaxy to repopulate without the psychic swarm, so they could emerge and reconquer their empire.
In combat, the Necrons are unyielding war machines that bring swift death to their prey. Armed with Gauss Weaponry that strip an opponent's molecules one layer at a time, the Necrons have fearsome firepower. Also, the Necrons have a remarkable ability to repair themselves, a Special Rule known as "We'll Be Back!". This gives the Necrons incredible staying power in a battle, which makes them an enemy dreaded by all races. It is often said amongst commanders of more orthodox armies that the Necrons are an over-powerful force on the battle field, due to the fact even a basic warrior can tear through the strongest tanks in the game although Necron players dispute this rigorously. They also use a variety of deadly wargear, including some types which make the wearer immune to some assaults, and others that create deadly arcs of lightning. These are analysed within the Necron Armoury.
The Necrons most often encountered by other races are warrior machines and are analysed in the Necron Army List. Necrons serving purposes other than purely warrior roles have not as yet been observed.
The Necron fleet is a small but deadly force capable of destroying most ships very easily. They also don't make use of the same form of interstellar travel, the warp, as other races do, making them difficult to intercept. Their fleets are analysed in the Necron Fleetforge. Also, on particularly rare occasions, a super heavy Necron device called a Necron Pylon is seen. It is feared for its extreme power and ability to appear anywhere on the battlefield.