The Grey Knights are a secret and mysterious Chapter of Space Marines specifically tasked with combating the dangerous daemonic entities of the Warp and all those who wield the corrupt power of the Chaos Gods.
They were created by the Emperor Himself with the aid of Malcador the Sigillite at the time of the Horus Heresy to serve as Humanity’s greatest weapon against the threat posed by the existence of Chaos.
They have the honour of being implanted with gene-seed engineered directly from the genome of the Emperor Himself.
The Grey Knights act as the military arm or “Chamber Militant” of the Ordo Malleus, the Daemonhunters who form the oldest branch of the virtually omnipotent Inquisition.