The Necrons are a completely robotic humanoid species whose technological prowess is probably unmatched by any of the other intelligent species of the galaxy. Yet out of a desire for vengeance against the more fortunate, long-lived, ancient xenos people called the Old Ones, and the trickery of the godlike intelligences known as the C'tan, the Necrons shed their original organic forms and lost all forms of compassion and empathy.
They have become instead ruthless, undying killing machines who are determined to exert their mastery over the galaxy once more. Across the galaxy, this ancient and terrible species is stirring back to life. Entombed in stasis-crypts for millions of Terran years, they have slumbered through the aeons, waiting for the galaxy to heal from the wounds of a long and bloody war.