The Holy Orders of the Emperor's Inquisition, more commonly known as the Inquisition, are the powerful secret police of the Imperium responsible for guarding the souls of humanity. The purpose of the Inquisition is to identify and destroy the myriad of potential threats to the Imperium and humanity. The organisation's members are agents known as Inquisitors.
The actual founding of the Inquisition is shrouded in mystery and there are at least two different stories surrounding its formation.
The first is that in the twilight hours prior to His internment within the Golden Throne, while Terra lay besieged by the traitor forces of Warmaster Horus, the Emperor of Mankind commanded Malcador the Sigillite to seek out "men of character, skill, and determination" to be tested and trained so that an elite group of investigators might be tasked to discover the alien, mutant, and heretic. Immediately prior to his assault on Horus's battle barge, Malcador presented twelve individuals to the Emperor - eight Astartes and four humans - whom he had gathered in response to the Emperor's commands. The Astartes were described as having cast aside their allegiance to their Primarchs and Legions who had sided with Horus; Malcador went on to say that they were blessed with paranormal skills which were best suited for combating the horrors that had recently emerged from the warp.
Although the identities of the twelve presented to the Emperor were never revealed, it is known that among those individuals recruited by Malcador were Captain Nathaniel Garro of the Death Guard, Captain Iacton Qruze of the Luna Wolves, and Sister of Silence Amendera Kendel.
The second story is that, immediately after the Emperor was interred in his Golden Throne, four trusted servants of the Emperor gathered in secret to discuss what was to happen next. Their opinions were divided; two believed the Emperor could be returned to life, the other two believed it folly to interfere with the events that had unfolded. The two resurrectionists, known as Promeus and Moriana, left Terra to begin their quest to bring the Emperor back to life. The two that remained acted quickly to establish themselves with the Senatorum Imperialis and created an organisation to combat the efforts of Promeus and Moriana, and it was from this seed that the Inquisition was formed.
It is not known whether these two stories are simply a case of conflicting background, or whether both stories contain some element of truth. It is said that when the Senatorum Imperialis was convened on the first anniversary of the Emperor's Ascension, a grim-faced man joined the council and identified himself as a representative of the Holy Orders of the Emperor's Inquisition. The fact that they called themselves "Orders" plural could be taken to suggest that the early Inquisition was an amalgamation of several organisations.
Ordos are a major operational subfaction within the Imperial Inquisition. As the Inquisition possesses neither a formalized hierarchy nor leadership, each Inquisition is free to pursue the mission of humanity's survival in the manner they see most appropriate. Like-minded individuals gather together to investigate areas of mutual interest and concern, as bounded by one of the many Inquisitorial Ordos. Each Ordo comes and goes with the times, for many Inquisitors move freely between them according to their own whims and judgement. Ordos can grow larger in crisis's and then exist only on paper until its field becomes relevant once more. Association with an Ordo is not a matter of absolute allegiance, nor does it preclude an Inquisitor's involvement in matters pertaining to another Ordo.
Currently within the modern Inquisition of M41 there are three Ordos Majoris (Xenos, Malleus, and Hereticus), and an unknown number of Ordos Minoris. These branches are ever-present for their mission is considered never-ending. Each branch specialises in the combat and investigation of specific threats to the Imperial domain. While Inquisitors from any Ordo are trained to deal with all potential dangers, it is the role of the Ordos to produce agents who are particularly adept at understanding and destroying specific abominations. Membership in an Ordo is not mandatory, and there are those Inquisitors who prefer not to join one.[Needs Citation]
- The Ordo Malleus (The Threat Beyond) - Destroys daemonic threats and investigates the nature of the Daemon. The Ordo came into being immediately after the Horus Heresy, and therefore has been a part of the Inquisition from the beginning.
- The Ordo Hereticus (The Threat Within) - Investigates and roots out heresy, mutation, and rogue psykers from humanity, and polices the Ecclesiarchy. The Ordo Hereticus was founded following the events of the Age of Apostasy.
- The Ordo Xenos (The Threat Without) - Investigates and eliminates alien influence and plots against the Imperium. It is not known when the Ordo Xenos was founded, however it is believed to be of a similar age to the Ordo Malleus.[Needs Citation]
In addition to the three major Ordos, there are a large but unknown number of Ordos Minoris.[22a]
- Ordo Aegis - Remains vigilant over the Cadian Gate.[22a]
- Ordo Astartes - Oversees the Adeptus Astartes.[22a]
- Ordo Barbarus - Monitors pre-Industrial worlds.[22a]
- Ordo Chronos - A ill-fated organization, all the members of which vanished.
- Ordo Custodum - Based on Terra.[22a]
- Ordo Desolatus - Unknown purpose[22a]
- Ordo Excorium - Monitors Exterminatus[22a]
- Ordo Machinum - Oversees the Adeptus Mechanicus[22a]
- Ordo Militarum - Oversees the Imperial Guard[22a]
- Ordo Necros - Unknown purpose[22a]
- Ordo Originatus - Tries to uncover the mystery of the Inquisition's origins.
- Ordo Redactus - Tries to keep the history of the Inquisition classified.
- Ordo Sanctorum - Oversees the Ecclesiarchy[22a]
- Ordo Scriptorum - Monitors Imperial records and communiques.[22a]
- Ordo Scriptus - Oversees Imperial historical records[22a]
- Ordo Senatorum - Unknown purpose[22a]
- Ordo Sepulturum - Researches current plagues afflicting the Imperium and determines how best to contain, destroy, and cure them. Created to investigate an increase in outbreaks of the Zombie Plague just before the 13th Black Crusade.
- Ordo Sicarius - Founded to police the activities of the Officio Assassinorum following the events of the Wars of Vindication which resulted from the events of Goge Vandire's Reign of Blood.
- Ordo Thanatos - Unknown purpose[22a]
- Ordo Vigilus - Oversees the Ordo Necros[22a]
Inquisitorial Conclaves, Cabals, and Cells
As well as the Ordos, there are many types of Inquisitorial groupings that an Inquisitor may belong to, however as with the Ordos, membership in these is not mandatory.[Needs Citation]
- Conclaves - Inquisitorial Conclaves can take two forms. The first is a gathering called by an Inquisitor (if called by an Inquisitor Lord it is termed a "High Conclave") to discuss a particular subject. There are also more permanent regional Conclaves; these are federations of Inquisitors who watch over a particular area of Imperial space. [7a] The larger of these regional Conclaves may have resources such as ships, armies, fortresses, and libraries for the use of their members. Not all sectors of Imperial space are covered by a Conclave, and some areas are devoid of a permanent Inquisitorial presence. The head of each regional Conclave is normally an Inquisitor Lord, and is nominally appointed by the High Lords of Terra. There are also Conclaves operating at the Segmentum level, again headed by an Inquisitor Lord.
- Cabals - A Cabal is a rare body instituted by a Conclave and dedicated to investigating a particular matter. Generally they gather Inquisitors from varied backgrounds and philosophies to form a specialist task-force. Often, Cabals are despised by many who see them as secret societies within a Conclave.[7a]
- Cells - Similar to a Cabal, a Cell is an ad-hoc group of Inquisitors who share a common goal. Often they are factional in nature, or are formed to confront a particular problem. The principle difference between Cabals and Cells is that the latter are entirely informal and are transitive in nature. Often one or more of the Inquisitors in the Cell will work overtly through investigation while the rest proceed through infiltration.
Role of the Inquisition
As a completely autonomous Imperial organisation beyond the power of the Adeptus Terra, the Inquisition is immensely powerful. As the Inquisition's duties involve the scrutiny and policing of the other organisations of the Imperium, the Inquisition itself is answerable to no higher power except the Emperor. No one, except the Emperor himself, is beyond the scrutiny of the Inquisition. This power is officially known as the Inquisitorial Remit or Inquisitorial Mandate.[Needs Citation]
With the exception of the Ministorum (which, in any case is still under outside Imperial restrictions), the Inquisition is the only organisation of Imperial government that is completely autonomous. Unlike other Imperial organisations, it is not a branch of the massive Adeptus Terra, but a self-contained organisation answerable only to itself. The Inquisition itself uses compounds scattered throughout the Imperium known as Inquisitorial Fortresses as its bases of operation.
The role of the ordinary Inquisitor is to investigate and deal with all potential threats to mankind and the Imperium. In the eyes of the Inquisition, there are multitudes of such potential threats. The main threat is posed not by invading aliens, but from within, by corruption and disloyalty within the Imperial organisations, as well as by psykers. The other threat posed from within is that of mutation, the constant corruption of the human gene-pool. There are no bounds to the Inquisition's area of responsibility: alien plots, mutation, political corruption, and incompetence all come under their jurisdiction.
If required, Inquisitors may call on the service and/or resources of any Imperial servant or organisation. Not even a High Lord of Terra may refuse the order of an Inquisitor without good reason. This power extends across the Adeptus Astartes and the Adeptus Mechanicus (however, learned Inquisitors show discretion and request the assistance of the Space Marines and attempt not to anger the Adepts of Mars).[Needs Citation]
The role of the Inquisition requires proactivity and efficiency unbound by the dogmatic bureaucracy common to most other Imperial departments. Accordingly, there is little in the way of hierarchy or departmentalisation within the Inquisition. Authority within the Inquisition is governed by two factors - reputation and influence. Seniority is in itself no indicator of authority, however most Inquisitors will take heed of the wisdom an older and more experienced peer. [7a]
Because the Inquisition are the watchdogs of the Imperium, answerable only to themselves, given almost absolute power, along with such broad jurisdiction, corruption is an ever present danger. Its integrity is therefore upheld by constant self-policing and scrutiny. In the earliest editions of the background, this was the stated role of the Ordo Malleus, which were the Inquisition's secretive Inner Order.[Needs Citation]
As per the Inquisitorial Remit, Inquisitors hold the absolute power to judge all who fall beneath their gaze. The Inquisition holds countless paths to death that usually correspond to the level of guilt of the condemned. The horrors of arco-flagellation, Penal Legion conscription, or binding to a Penitent Engine are a small sample of unique forms of penitence and absolution that Inquisitors use on a regular basis.[Needs Citation]
Inquisitors have the authority to condemn an entire world to Exterminatus if it is deemed to be irredeemably corrupt. Exterminatus, the obliteration of a world, is only resorted to when the level of corruption a world bears is so monumental that it cannot be wiped out by any other means.[Needs Citation]
Although there is no formal structure of rank or command in the Inquisition, save for the recognition that the Emperor is the highest ranked figure and supreme commander,[7b] there are a number of positions that may be held by an Inquisitor. These positions do not bring any more authority (an Inquisitor's authority is already absolute), however the incumbent Inquisitor will have increased influence over his peers by virtue of his office. The powerful Inquisitorial Representative represents the organization on the High Lords of Terra.
Recruitment and Promotion
Recruitment within the Inquisition is not centralized, and an Inquisitor is free to recruit whoever he so chooses as an acolyte. There are many different names given to acolytes – Interrogator, Explicator, Neophyte, Novitiates, Approbators, etc. - but in themselves they carry no authority (only that which they are granted by their Inquisitor) . Although some Inquisitors may have their acolytes pass through various "ranks" on their progression to Inquisitor, those ranks are not standardized across the Inquisition. However, within individual conclaves there may be established conventions for temporarily granting the Inquisitional remit to an acolyte within the scope of a particular assignment. Within the Calixis and surrounding sectors such an individual is known as a Legate Investigator. Legates are identified by an icon known as a Sigil of Question which contains features similar to a rosette, and a Carta of Inquiry which describes the scope of their investigation.
For an acolyte to be raised to the rank of Inquisitor, the consent of three Inquisitors or an Inquisitor Lord is required. There have been cases where the situation has called for an acolyte to take on full Inquisitorial responsibilities immediately without the blessing of three Inquisitors or a Lord. For example, if an acolyte's Inquisitor is killed in action, he or she may inherit their Inquisitorial Seal and fulfil the role of an Inquisitor subject to repeal by another Inquisitor.
An Action is how the Inquisition interrogates its prisoners.
Although an Inquisitor can employ the services of any branch of the Imperial service, including the military, each major Ordo also maintains a dedicated Chamber Militant representing the most dedicated, experienced, and effective forces that Ordo can call on.
- The Ordo Malleus' Chamber Militant are the Grey Knights.
- The Ordo Hereticus' Chamber Militant are the Orders Militant of the Adepta Sororitas, also known as the Sisters of Battle.
- The Ordo Xenos' Chamber Militant are the Deathwatch.
To the conservative Puritans, it is of the utmost importance that Inquisition doctrine be upheld, and they are often found persecuting those Inquisitors who are deemed heretical. The more pragmatic Radical Inquisitors follow the Imperial doctrines in spirit, believing that the ends justify the means, and find little value in adhering to convention too closely. They often try to fight fire with fire, using Chaos or Xenos weaponry, employing Daemonhosts, or committing other acts that would be deemed heretical by their more conservative brethren.[Needs Citation]
Inquisitors of both sides are found in great number, and while often at odds with each other, are equally interested in the survival of mankind and the defeat of its enemies. Puritans and Radicals are further divided into individual philosophies, leading to further friction.[Needs Citation]
- Inquisitor Lord Hector Rex - Ordo Malleus, Proctor-General of the Conclave of Scarus, Master of the Thirty-Fourth Chamber Practical, the Victor of Hellanus, Saviour of Vraks. 
- Inquisitor Lord Torquemada Coteaz - Ordo Malleus, High Protector of the Formosa Sector 
- Inquisitor Lord Fyodor Karamazov - Ordo Hereticus, Pyrophant Judge of Salem Proctor 
- Inquisitor Lord Bronislaw Czevak - Ordo Malleus, One of only a few that has been granted access to the Eldar Black Library of Chaos
- Inquisitor Lord Kryptman - Ordo Xenos, Hero of the Macharian Heresy
- Inquisitor Helynna Valeria - Ordo Xenos 
- Inquisitor Gideon Lorr - Ordo Hereticus 
- Inquisitor Solomon Lok - Ordo Xenos, Chief Investigator of the Anphelion Incident 
- Inquisitor Emil Darkhammer - Ordo Hereticus, declared Excommunicate Traitoris 
- Inquisitor Amberley Vail - Ordo Xenos - worked alongside Commissar Ciaphas Cain
- Inquisitor Jaq Draco - Ordo Malleus, Renegade Inquisitor who raided the Black Library and stole the Book of the Rhana Dandra
- Inquisitor Gregor Eisenhorn - Ordo Xenos, famour Inquisitor that killed the renegade Inquisitor Quixos
- Inquisitor Gideon Ravenor - Ordo Xenos, Previously an acolyte to Inquisitor Gregor Eisenhorn
- Inquisitor Quixos - Ordo Malleus, A radical Inquisitor who was eventually slain by Inquisitor Eisenhorn
- Inquisitor Silas Hand - Ordo Malleus, Radical Inquisitor and antagonist of the Daemonifuge graphic novels
- Inquisitor Mordecai Toth - Ordo Malleus, Investigated the daemonic presence on Tartarus
- Inquisitor Adrastia - Ordo Malleus, Investigated the daemonic presence on Aurelia
Inquisitors were not well known in the Warhammer 40,000 universe until the release of the 54mm miniatures game Inquisitor, which is a narrative game, based around warbands often composed of an Inquisitor and his henchmen. The creation of Inquisitor was followed by a great deal of information about the Inquisition, and the organisation attracted the interest of fans. This led to the creation of Codex: Daemonhunters and Codex: Witch Hunters, both based around armies led by Inquisitors (of the Ordo Malleus and the Ordo Hereticus, respectively).
- 1: Warhammer 40,000: Rogue Trader, [Needs Citation]
- 2: Codex: Daemonhunters (3rd Edition), [Needs Citation]
- 3: Codex: Witch Hunters (3rd Edition), [Needs Citation]
- 4: Codex: Assassins (3rd Edition), [Needs Citation]
- 5: Codex: Grey Knights (5th Edition), [Needs Citation]
- 6: Codex Imperialis pg. 31
- 7: Dark Heresy Rulebook
- 8: Dark Heresy: Disciples of the Dark Gods, [Needs Citation]
- 9: Dark Heresy: The Inquisitor's Handbook, pgs. 64-65
- 10: Black Crusade Core Rulebook, pg. 321
- 11: White Dwarf #304, [Needs Citation]
- 12: Imperial Armour Volume Two - Space Marines and Forces of the Inquisition, pg. 192
- 13: Imperial Armour Volume Four - The Anphelion Project, [Needs Citation]
- 14: Imperial Armour Volume Seven - The Siege of Vraks - Part Three, [Needs Citation]
- 15: The Flight of the Eisenstein (Novel) by James Swallow, [Needs Citation]
- 16: Malleus (Novel) by Dan Abnett, [Needs Citation]
- 17: Horus Heresy: Visions of Death by Alan Merrett, [Needs Citation]
- 18: Thorian Sourcebook, [Needs Citation]
- 19: The Thorians: Faction Sourcebook, (last retrieved on 2006-03-28), [Needs Citation]
- 20: Inquisitor, 1st Edition ISBN 1-84154-077-3, pg. 30
- 21: Black Library Blog, entry dated August 8, 2012 (last accessed August 8, 2012)
- 22: Codex: Inquisition pg.8-9
- 22a: pg.18