"Exitus Acta Probat: The Outcome Justifies the Deed."
The Grand Master of Assassins
The Officio Assassinorum, or Office of Assassins, is one of the most secretive organizations in the Imperium. Its hidden Grand Master is one of the High Lords of Terra, the cabal of awesomely powerful individuals whose every decision affects untold billions of people and immerse tracts of the Imperium.
Only the High Lord themselves can sanction the deployment of the Assassins, for fear that their own weapons may be used against them. It is said that in the distant past the Grand Masters used Assassins to further their own ends, and a reign of terror clutched even the High Lords themselves. In the anarchic Wars of Vindication the Grand Master himself fell to the Assassin's knife. Thereafter, the High Lords took special care to control the Officio Assassinorum so that, in theory, only traitors and heretics need fear it today.