In 4993 Alexius Hawkwood was crowned Emperor of the Known Worlds. Three years later all bowed before him recognising his claim. In the years since his ascension Alexius I has instigated many potent reforms to both consolidate his power and revive an Empire crushed by decades of war.
Although the current leader of the Known Worlds is technically a noble, the Emperor has distanced himself from his House of birth. Like other major estates of power the Imperium has several factions that make themselves felt upon the known worlds. Some old some new these Factions all swear allegiance to the Emperor himself. These factions are bureaus of the Imperial Government.
The Imperial Eye is the Intelligence agency of the Imperium. Originally established by Emperor Vladamir Alecto it often schisms between the loyalties of the Old Guard to the new loyalties of the Angels. The Imperial Eye are everywhere and have mandates to recover lost technology and lost worlds
The Phoenix Guard form the Sentinels of the Known Worlds. They are the Emperor's Elite Guards. Armed with the best technology the Emperor can buy they are considered to be in direct competition with the Brother Battle for the title of Most Elite Fighters of the Known Worlds.
As part of the on going war against the Symbiots the Empire has a long term standing army stationed on Stigmata.
The Imperial Fleet is the remains of the Second Republic stellar fleet originally resurrected by Vladimir in his ascension to power and then used by the Regent to enforce their mandate. Now under the control of Emperor Alexius he uses it to maintain peace and police the spacelanes for pirates.