Segmentum Ultima

The Segmentum Ultima is the Segmentum of Imperial space to the galactic east of Terra. The Ultima Segmentum contains the Galactic Core. The Ultima Segmentum is home to the largest number of worlds in the Imperium as it is the largest of the Segmentums. 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. In terms of its sheer size and volume this is the largest Segmentum of the Imperium of Man. The galactic core resides within its space. The Eastern Fringe of this region of the galaxy lies the most distant from the Astronomican. Ork empires, pirate conclaves and Tyranid incursions are the main threat within this oft volatile region of the galaxy.

Notable Regions
The major features present in this region of the galaxy include:
 * Storm of the Emperor's Wrath - A notable and fiercely persistent Warp Storm which has raged since the Age of Apostasy.
 * Maelstrom - The Maelstrom is a massive and ancient Warp Rift near the galactic core. This area of space is riven with Warp Storms so intense that stellar travel in the region is virtually impossible. Second only to the great Warp Rift that is the Eye of Terror, the Maelstrom scars both the physical universe and the fabric of the Immaterium beyond. This volatile region of space has become a haven to pirates, criminals and renegades such as the Red Corsairs Chaos Space Marines as well as gateways to the Dark Eldar's Webway city of Commorragh, who use it as a base from which to launch raids on Imperial space.
 * Realm of Ultramar - The feudal demesne comprising 11 worlds which is administered by the Ultramarines Chapter of Space Marines.

Notable Systems

 * Baal System
 * Badab System

Notable Planets

 * Attila - Imperial Feudal World that maintains a late Iron Age civilisation and almost no advanced Imperial technology. This barbaric world is also the homeworld of the famed Rough Riders of Attila Mounted Regiments of the Imperial Guard.
 * Baal - Arid Desert World and Chapter homeworld of the Blood Angels Space Marine Chapter.
 * Badab -
 * Catachan - Death World and homeworld to the famed and deadly Imperial Guard Regiments of the Catachan Jungle Fighters.
 * Mundus Planus (Chogoris) - Feudal World of savage horse nomads who maintain little advanced Imperial technology. Homeworld of the White Scars Space Marine Chapter.
 * Golgotha - Golgotha is an Ork world, conquered and infested by the forces under the command of Ghazghkull Mag Uruk Thraka after the Second War for Armageddon.
 * Kar Duniash - Kar Duniash is the Segmentum Fortress of Segmentum Ultima as well as the headquarters for the Imperial Navy Battlefeet Ultima. It is also the site of a major Imperial shipyard which is the primary builder of the Dominator-class Cruiser.
 * Nocturne - This dual-classed Feudal World/Death World is the Chapter homeworld of the Salamanders Space Marine Chapter.
 * Pavonis - A troubled Industrial World located on the Eastern Fringe. The Ultramarines 4th Company under the command of Captain Uriel Ventris was sent to quell the troubles in the form of both human and xenos alike. A secret, heretical organisation, known as The Church of the Ancient Ways, plagued the planet with random bombs planted around the various planet's manufactorums. In addition the world was also continuously raided by Dark Eldar corsairs over the course of six years. Uriel Ventris was successful in defeating both the civil insurrection as well as crushing the Dark Eldar and their human collaborator in the hidden tomb of the C'tan Shard known as the Nightbringer. Unfortunately, this vile entity escaped the confines of its tomb and fled into the galaxy at large.
 * Prometheus - Large moon which orbits the Death World of Nocturne and serves as the location for the fortress-monastery of the Salamanders Space Marine Chapter.
 * Valhalla - Frigid Ice World of the famed Imperial Guard Regiments of the Valhallan Ice Warriors.