A Psyker is an individual of any intelligent species in the Warhammer 40,000 universe who possesses some degree of psychic ability or powers. Psychic powers are sometimes referred to as "sorcery" and their users as "witches" in the Imperium of Man and among the Eldar, particularly when such powers are used in such a way that they show no regard for the dangers they may spawn for others or are used in pursuit of the agenda of the Chaos Gods.