The Segmentum Ultima, also known as the Ultima Segmentum, is the Segmentum of Imperial space to the galactic east of Terra. The Ultima Segmentum contains the uninhabitable core of the Milky Way Galaxy which is marked by a super-massive black hole. The Ultima Segmentum is home to the largest number of worlds in the Imperium of Man as it is the largest of the Segmentums in terms of its sheer size and spatial volume. It contains the Ultramarines' Realm of Ultramar. It has seen attacks by two separate Tyranid Hive Fleets, including Hive Fleet Behemoth and Hive Fleet Kraken. The Eastern Fringe of this region of the galaxy lies the most distant from the Astronomican. Ork empires, pirate conclaves, the expansionist Tau Empire and Tyranid incursions are the main threat within this oft-volatile reg