Gregor Eisenhorn

Gregor Eisenhorn is perhaps the most famous Inquisitor in all the Imperium's grim history, an agent of the Ordo Xenos whose long career traces a single, terrible arc: the slow corruption of a righteous man by the very evils he was sworn to destroy. He began his service as a puritan of the Amalathian persuasion, a believer in stability and orthodoxy who would have recoiled from the compromises his later self came to embrace. Yet decades of confronting horrors that no clean method could defeat wore that certainty away, and by the twilight of his career Eisenhorn had drifted into the radical philosophy of Xanthism, willing to turn the weapons of the enemy against the enemy.

That willingness made him a legend and damned him in equal measure. Twice at the least the Inquisition formally proclaimed him a traitor, and twice he was vindicated, proven a loyal servant of the Emperor even as his methods grew ever darker. His most infamous transgression was the binding and use of the daemonhost Cherubael, a being of the warp chained to his will, a tool of appalling power that preserved his life and his missions more than once, and that ultimately marked him, in the eyes of his peers, as the heretic he had spent a lifetime hunting.

Xenos, Malleus, Hereticus

Across the investigations chronicled in the three great accounts of his life, Eisenhorn pursued foes worthy of his cunning. He hunted a heretical cabal to the world of the enigmatic Saruthi, who had obtained a copy of the dread Chaos tome known as the Necroteuch and rendered it into their own alien tongue; the High Gothic version he found and destroyed with his own hands. Time and again he walked willingly into damnation to prevent a greater one, telling himself each time that the line he had just crossed would surely be the last.

What makes Eisenhorn so compelling a figure is precisely that he is never quite the villain nor quite the hero. He remains, to the very end, a man convinced of his own righteousness, employing ever more monstrous means in service of an end he still believes just, a mirror held up to the Inquisition itself, and to the Imperium that both needs and fears the men it makes of people like him.