Inquisition - Ordos Majoris: In early editions of Warhammer 40,000, the Inquisition was a single, undivided organisation -- purposefully outside the bureaucracy of the rest of the Imperium -- with a single inner order, the Ordo Malleus. The Malleus' purpose was to police the Inquisition itself. Its other, secret purpose was dealing with the threat of Chaos.Today, the Inquisition is divided into a series of organisations known as "ordos." Each ordo is responsible for assessing and combating a threat to Humanity.There are three Ordos Majoris devoted to combating threats to the Imperium from within, without, and beyond.Ordo Malleus - Known as the "Daemon Hunters," or the "Order of the Hammer," the Ordo Malleus are sworn to defend the very soul of Mankind, concentrating on the defeat of those enemies of Humanity that dwell in the warp; the so-called "enemy beyond." They primarily concern themselves with destroying Daemons and other servants of Chaos. They have pledged their every waking hour to the discovery and scourging of such creatures, wherever they can be found. Members of the Ordo Malleus are often battle-hardened warriors, for Daemons cannot be cast out through the subtleties of espionage or trickery – only the blessed blade and the purified flame will serve. However, knowledge is their chief weapon. Agents of the Ordo Malleus are scholars of daemonic lore and know how to shackle and bind Warpspawn. Militarily, the Ordo Malleus is the most formidable of the Inquisition's branches, for its agents can call upon the services of their Chamber Militant, the Grey Knights, to aid them in their struggles. The Grey Knights are Space Marines, designated Chapter 666. Unlike other Chapters of the Adeptus Astartes, who are called upon to fight any and all threats to the Imperium, the Grey Knights are dedicated to slaying Daemons and stand ever ready to assist the Ordo Malleus in their long war against Chaos.Ordo Xenos - Also known as the "Alien Hunters", or the Order of the Aliens, the Ordo Xenos are dedicated to investigating, cataloguing and defeating the Xenos threat; the enemy without. They actively seek out and eliminate alien influence and corruption within the Imperium. Agents of the Ordo Xenos are typically the most eccentric of their kind, for they spend years – even decades – travelling and living in nonhuman space, learning everything they can that will facilitate the exploitation or elimination of the races they encounter. As a result, many Ordo Xenos Inquisitors have strong ties with Rogue Traders, with whom they share many goals, and often travel with retinues of alien mercenaries or travellers. Most speak dozens of nonhuman languages and have acquaintances and informants far beyond the Imperium's boundaries. Despite this, there is more blood on the hands of the Ordo Xenos than any other branch of the Inquisition. Just as the Ordo Malleus can call upon the Grey Knights, so too can the Ordo Xenos call upon the services of their own Chamber Militant, the Deathwatch. Formed long ago by accord between a conclave of Inquisitor Lords and an esteemed assemblage of Space Marine Chapter Masters, the Deathwatch is composed entirely of veteran Space Marines, seconded from the greatest Chapters in the galaxy. They are trained and equipped to repel the alien tide that threatens to overwhelm Humanity, and are an invaluable tool for any Inquisitor seeking to vanquish the xenos threat.Ordo Hereticus - This Ordo is also known as the "Witch Hunters", or the Order of the Heretics. The Ordo Hereticus is the scourge of Traitors, witches, Mutants, Rogue Psykers and Heretics. The interests of its members are aligned towards the combating of threats broadly classified as arising from within the great bulk of Humanity; the so-called "enemy within." The Witch Hunters of the Ordo Hereticus are sinister, feared individuals. Their skin is pale from long days spent in the excruciation chambers of Inquisition fortresses or poring over ancient texts that speak of the heretic and his machinations. The arrival of an Ordo Hereticus Inquisitor is met with as much trepidation as awe, since none know where their gimlet gaze may land and upon whom their suspicions might fall. In addition to monitoring the Ecclesiarchy – ensuring that Wars of Faith do not exceed their mandate or that its many Cardinals do not amass more power than is deemed appropriate – the Ordo Hereticus keeps a close eye on many other Imperial organisations: the Adeptus Arbites, the Adeptus Astartes, the Adepta Sororitas and also fellow members of the Inquisition. They monitor doctrinal and physical purity, and no one is beyond their jurisdiction. The Ordo Hereticus can also call upon their own Chamber Militant, the Sisters of Battle, the all-female warrior branch of the Adepta Sororitas. It should also be noted that there are some freelance Inquisitors-at-large who are not part of one specific branch of the Inquisition. There are also several minor Ordos that have more specific purposes than those outlined above.