The Calixis Sector is located in the Segmentum Obscurus, on the northern edge of the known galaxy, and represents a portion of the considerable territories conquered by the Imperial hero Lord Militant Angevin more than a thousand years ago. Its first governor was Drusus, one of Angevin’s most capable generals, a man now revered as an Imperial Saint.
The Calixis Sector has many heavily populated and important worlds, but it lies a great distance from the Imperium’s heartland and, like so much of the Imperium, it must ultimately fend for itself. Like all Imperial territories, the Calixis Sector is at risk from the chronic dangers facing humanity: war, mutation, xenos activity, the mark of Chaos, and so on. However, a singular threat lurks somewhere in the Calixis Sector, a mysterious, prophesied doom that has drawn the particular scrutiny of the Inquisition to this collection of worlds. This enigmatic threat, the Hereticus Tenebrae, or the Tyrant Star as it is known, is something the forces of the Inquisition most fervently wish to uncover, to comprehend and to destroy, before it is too late.
To trailing, the Calixis Sector is bordered by the hazardous territories of the Fydae Great Cloud and to spinward by the Scarus Sector. Bordering to coreward, its nearest neighbour is the Ixaniad Sector. To rimward lay the contested and unregulated frontiers of the Halo Stars.