"We are the warriors of the Grey Knights, armoured in faith, shielded by devotion and armed with purity of purpose.
But greater even than these, we carry the light of the divine Emperor of Man into the dark places to purge the Daemonic wherever it may be found." The Grey Knights are a secret, mysterious Loyalist 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 have the honour of being implanted with gene-seed engineered directly from the genome of the Emperor Himself.
The Grey Knights' Fortress-Monastery is based on Titan, the largest of the moons of the gas giant Saturn in the Sol System, that is kept as a private preserve of the Inquisition.
The existence of the Chapter is virtually unknown outside of the Inquisition and the highest echelons of the Imperial Adepta, and is a well-guarded secret enforced by mind-wipes and even assassination of Imperial citizens if necessary.
Unlike other Astartes, every Grey Knight is a potent psyker.
Yet, in the 10,000 standard years of Imperial history, no Grey Knight has ever been corrupted by the Ruinous Powers of Chaos.
A light against the darkness, the Grey Knights stand against the greatest threat Mankind has ever faced.
They are the champions of reason, order and righteousness, holding back Daemons and the scions of the Dark Gods.
They are the Imperium's mightiest weapon against the Warp, superhuman Space Marine psykers, and its single enduring hope for salvation.
There is no greater threat to the galaxy than the denizens of the Warp and the Ruinous Powers that rule them.
Daemons and gods, these otherworldly horrors tear at the veil between the Realm of Chaos and reality, hungry for the souls of men and the ruin of worlds.
If left unchecked and unopposed, Daemons would claim the universe for their own, pulling down the pillars of creation and fashioning a never-ending nightmare where once the galaxy had been.
Daemons are unlike any other foe the Imperium faces, and against their unnatural horror men can find themselves powerless.