The Chamber Militant is the military arm of each branch of the Imperial Inquisition. The Ordo Xenos (Alien Hunters) is served by the Deathwatch Space Marines, the Ordo Malleus (Daemon Hunters) by the elite Grey Knights Space Marine Chapter and the Ordo Hereticus (Witchhunters) by the Adepta Sororitas, the Sisters of Battle. Usually, these organisations are only called upon by their Ordo in cases of dire need, when all other options have to deal with a given situation have been exhausted. For example, the Grey Knights are called upon only when a daemonic infestation has grown to the point that the efforts of a lone Inquisitor and his Acolytes can no longer contain it.
- Warhammer 40,000: Dark Heresy Core Rulebook (RPG)
- Warhammer 40,000: Deathwatch (RPG)
- Codex: Grey Knights (5th Edition)
- Blood of Martyrs (RPG)