Radicals are a political and philosophical faction of the Inquisition. Setting themselves apart from the more conservative Puritans, the 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. Their experimentation with these forces often leads to them being branded heretics, or succumbing to the very power they sought to control.
- Antiquarti- Focus on discovering patterns and events in the past to predict the future.
- Casophilians- Dedicate their studies to the transition of a Human soul from this world to the next.
- Horusians- Believe that the power of Chaos that manifested in Warmaster Horus might be harnessed for the creation of a Divine Avatar.
- Istvaanism- Believe conflict is desirable to further progress through strife.
- Libricars- Believe in the widespread purging of all Imperial institutions of all corruption and heresy, no matter how minor.
- Oblationists- Believe that the Warp, the xenos and the unclean are utterly damning, yet their use is necessary to overcome mankind's enemies.
- Ocularians- Obsessed with predicting and divining the future through arcane rituals.
- Phaenonites- Believe in the rebirth of the Imperium under their own leadership. Excommunicate Traitoris.
- Polypsykana- Believe in the ascension of Humanity into a purely psychic race.
- Recongregationism- Believe that the Imperium should be rebuilt, lest it stagnate further and collapse under the pressure of countless threats from both without and within.
- Revivificators- Goal is the study of the transition of the soul to the Warp at the moment of death.
- Seculos Attendous- Maintains that the Ecclesiarchy is hampering and holding back mankind, and therefore they seek to reduce its power and influence where possible.
- Xanthism- Advocates the use of Warp-based weaponry, such as daemon possessed swords, daemonhosts, and generally turning the power of Chaos against itself.
- Xeno Hybris- Believe that Mankind must learn from both the achievements as well as the mistakes of Xenos races.
Notable Radical Inquisitors
- Ordo Xenos: Gregor Eisenhorn (Late career), Konrad Molitor, Helynna Valeria, Thaddeus Hakk, Arrius Balk
- Ordo Hereticus: Silas Hand, Ernst Stavros Killian, Alders Terhan
- Ordo Malleus: Golesh Heldane, Querrian, Quixos, Gholic Ren-Sar Valinov, Suresya