Psyker
In the fictional universe of Warhammer 40,000, psykers are individuals with some form of psychic ability. Psykers draw their power from the Warp, a parallel universe of pure energy. Because the Warp is inhabited by daemons, psykers are often at risk of insanity or daemonic possession.
Read more about Psyker: Psykers of Different Races, Psyker Levels, Anti-Psyker Weaponry, Controlling Psykers, Bibliography