Please add your entries to the updated 40K Galaxy Index. I have included all previous contributions.

Accatran Ultima Segmentum. A Forgeworld of medium importance, homeworld to the Legio Destructor Titan Legion (The Beasts of Steel). Located near the Ork Empire of Caradon

Adrantis Five: (Segmentum Pacificus) Hyper-technical human-populated planet that had been isolated from the Imperium for over five thousand years. They had "turned to the dark certainties of science, and created many new and wondrous machines." Adrantis Five held Macharius at bay for two years before it was eventually destroyed by a re-directed comet. "Of its secrets, nothing now remains."

Agripinaa Segmentum Obscuras. An extremely important forgeworld situated near the eye of terror. Its proximity to the fortress world of Cadia, means it is the principle supplier of arms to the forges of the Cadian Gate. Was attacked by the World Eaters during Abbadon’s 13th Black Crusade but was successfully defending by Imperial Forces, including the Blood Angels Space Marine Chapter.

Antioc Segmentum Obscuras. Used to be a Forgeworld of medium importance until it was attacked an overrun by the forces of Chaos.

Alesma VII: Alesma 8 (part of the Virgonian cluster of star-systems in the delta segmentum, and the only inhabitable planet in its system) is actually a large moon left in orbit after it's anchor-world was destroyed in M.32. It's surface is barren and void of ANY sign's of life (save the refuge and centuries old shrapnel of marine technology blasted to its powdery white surface aeons ago when its homeworld was fought for between marines), yet underneath its surface lies an advanced and heretical society that had long ago turned its back on the empire. After having been out of touch for almost a thousand years, thier people began to consider the empire a strange folk tale from the old people's generation. Having been left to thier own devices for 7000 years, they developed a wonderful and harmonious subteranean culture, growing more complacent and advanced in thier sciences, eventually reaching out for the nearby balls of uninhabitable rock and attempting terra-formation.
At this point, Imperial Psyker's began recieving a faint sound from thier part of the universe, alarming them and their superiors. Currently, the Inquisition has been informed, and has taken flight towards Alesma 8.

Alsanta: (Ultima Segmentum) Ork homeworld of the Warchief of Alsanta, whose Waaagh overran at least five Imperial worlds between 450-996.M41.

Armageddon: (Segmentum Solar) Imperial Hive world. Site of three major wars against the Imperium. In the First War for Armageddon, Chaos forces led by the Daemon Primarch Angron invaded Armageddon, but were eventually driven off by a combined Imperial force which included the Space Wolves and Grey Knights Space Marine chapters. The Second and Third Wars for Armageddon saw Ghazghkull Thraka and his Ork minions battling for control of the Hive world to no avail, although Imperial losses were tremendous. Both Angron and Ghazghkull have independently vowed to return to Armageddon to witness its destruction! Footnote: at least one presumed Necron pyramid has been found in Armageddon's equatorial jungles.

Arx: (Segmentum Obscurus) Imperial research outpost and monitoring station that monitors the Arx Gap, an alternate route out of the Eye of Terror that bypasses the Cadian Gate. Abaddon the Despoiler raided the station in 139.M41 which marked the beginning of the Gothic Wars.

Attila: (Ultima Segmentum) Imperial Feudal world. Homeworld of the Attilan Rough Riders. Attila is somewhat smaller than Earth and has a single continent that covers almost half its surface. The center of this massive land mass is prone to such extremes of temperature that it reamins uninhabited, a baking desert in the summer which becomes a subzero sea of sand and snow in the winter. The bulk of the population are nomads who subsist from their herds of ovigars, gigantic shaggy and savage animals native to Attila.

Avellorn: (Segmentum Solar) Imperial Hive world. Site of a battle between loyal Imperial forces and the Iron Warriors during the Horus Heresy.

Avignor: (Segmentum Obscurus) Diocese of Avignor, presided over by Cardinal Armandus Hellfire. Adeptus Ministorum relic, Scepter of Avignor, enshrined here.

Baal: (Ultima Segmentum) Desert Homeworld of the Blood Angels Space Marine chapter. Consists of Baal and its twin inhabited moons, Baal Prime and Baal Secundus. In ancient days, Baal and its moons had earth-like atmospheres. Baal itself was a world of red rust deserts but its moons were veritable human paradises. However at the end of the Dark Age of Technology, viral and nuclear weapons decimated Baal and its moons. The few survivors were often horribly mutated due to the radioactive and chemical toxins that polluted the worlds and the once prosperous civilization devolved into a collection of tribal bands, some even resorting to cannibalism. Sanguinius, Primarch of the Blood Angels, landed on Baal Secundus as an infant and rose to god-like preeminence among the people of Baal. Upon meeting the Emperor, who had travelled to Baal in a quest to find his lost children, Sanguinius immediately recognized his father and bowed his knee before the Lord of Mankind. The Emperor blessed Sanguinius and thus the Blood Angels were founded. To this day, the Blood Angels recruit from among the greatest tribes of Baal Secundus and Baal Prime in a ritual that transforms the mutated aspirants into restructured superhumans that reflect both the physical beauty and personality of their primarch, Sanguinius.

Badab: (Ultima Segmentum) Homeworld of the renegade Astral Claws Space Marines (cleansed). Huron Blackheart, Master of the Red Corsairs, AKA Lufgt Huron, Tyrant of Badab, Lord of the Maelstrom, was grievously wounded by a melta blast near the end of the siege of Badab by Imperial forces. He survived (now almost half of his body is fitted with bionics) and his renegade Space Marine followers escaped to the Maelstrom from whence he leads raids with growing frequency. More disturbing is the distinct possibility that loyal Space Marines that have disappeared are later found fighting in Huron Blackheart's armies!
Bakka: (Segmentum Tempestus) Imperial Segmentum Tempestus Naval Base. During the First Tyrannic War in 745.M41, a battlefleet was despatched from Bakka to aid in the battle for Macragge.

Balur: (Ultima Segmentum) Ork world. Purged by Imperial forces led by Marneus Calgar of the Ultramarines Space Marines and which included Nork Deddog, Ogryn hero (his first battle, assigned to the 2nd Catachan Regiment).
Barac: (Segmentum Solar) Imperial world, recruited troops to fight against the Ork invasion of Ryza.

Beta Anphelion IV - Segmentum Tempestus. Fourth moon of the gas giant Beta Anphelion, located in the Anphelion system. A planet with an ammonia-rich atmosphere, first discovered by the Rogue trader Court Van Meer in M.35. The location of a top-secret research facility conducting experiments upon captured members of the Tyranid race. Inquisitor Soloman Lok was sent to the planet in M.41, by Inquisitor-Lord Varius to investigate the facility. He was assisted by the 266th Cadian regiment, the D-99 Elysian Detachment and a company of Red Scorpions Space Marines. None save the Red Scorpions survived the mission.

Biegel-9 Segmentum Unknown. World upon which the radical inquisitor Ralei founded a Xenos zoo. Here he kept numerous xenos species which he one member of staff studied. The facility was discovered by other members of the inquisition upon Ralei’s death and was investigated by one Inquisitor Sasham. The facility was destroyed soon after. The details of this investigation can be found in the book “Xenology” from the Black Library.

Boras Minor: (Ultima Segmentum) Agri-world. During the Age of Apostasy High Lord Vandire orders an invasion, enslaving every female child under twelve years of age.

Bork: (Ultima Segmentum) Ork homeworld of the Mighty Mangler of Bork, whose Waaagh overran at least five Imperial worlds between 450-996.M41.

Bray: (Segmentum Obscurus) Imperial outpost. Fabius Bile is known to have landed on Bray.

Cadia: (Segmentum Obscurus) Closest significant Imperial world to the Cadian Gate, homeworld to the Cadian Shocktroops. Cadia has become a staging point for Imperial forces protecting the Cadian Gate from Chaos incursions emanating from the Eye of Terror.

Cadian Gate: (Segmentum Obscurus) A narrow corridor of stable space on the galactic southeast edge of the Eye of Terror. The Cadian Gate is the only predictably stable passage out of the Eye of Terror, and is therefore the site of frequent raids by the forces of Chaos.

Caliban: (Segmentum Obscurus) Home planet of the Dark Angels Space Marines. Once a lush planet covered in forests, Caliban was destroyed after the defeat of Horus by a civil war between the loyal Primarch Lion El' Jonson and the traitor Luther. A remnant of the planet and the rebuilt fortress monastery was fitted with engines and travels throughout the galaxy as the Rock, recruiting Space Marine candidates from nearby worlds.

Calth: (Ultima Segmentum) One of the most productive planets of Ultramar, Calth is an airless world whose inhabitants live in underground cities. Calth is famous for its shipyards, which provide the craft used by the Ultramarines as well as civil and military craft for wider use throughout the Imperium.

Calverna: (Segmentum Solar) Ork homeworld of the Arch Maniac of Calverna, whose Waaagh overran at least five Imperial worlds between 450-996.M41.
Carpathia: (Segmentum Solar) Imperial world. Attacked by Tyranid Hive Fleet Leviathan in 997.M41. Declared Perdita by the Inquisition.

Catachan: (Segmentum Solar) Imperial Death world. Famous for its thick jungles, Catachan raises "Jungle Fighters" which are known throughout the Imperium as some of the toughest Guardsmen on the battlefield. Home to the Catachan Devil (giant scorpian-like animal), Brainleaf, Spiker, and Venus Mantrap (carnivorous plants).

Charadon: (Ultima Segmentum) Ork homeworld of the Arch Arsonist of Charadon (Warlord Snagrod), whose Waaagh overran at least five Imperial worlds between 450-996.M41.

Chiros: (Segmentum Pacificus) Lush homeworld of Confessor Dolan, known for its export of luxury goods such as exotic furs, elixers, and narcotics. Through the preaching of Confessor Dolan, Chiros was the first system to resist Cardinal Bucharis' control. Other systems stimulated by the Confessor's fiery sermons rebelled against Bucharis' cruel regime, which eventually led to the tyrant's ultimate demise.

Colcha: (Segmentum Pacificus) Agri-world which successfully rebelled against the Apostate Cardinal Bucharis' control. Enraged with "righteous ferver" instilled by Confessor Dolan, the entire population uprose against Bucharis' regime, driving his forces from the system.
Cypra Mundi: (Segmentum Obscurus) Forge World. Segmentum Obscurus Naval Base.

Dacia: (Segmentum Tempestus) Adeptus Mechaincus Explorator Base, destroyed by the Tyranid Hive Fleet Leviathan invasion of 997.M41.

Delta Tao: (Ultima Segmentum) Imperial planet (and sector) likely infested with Genestealers. The entire sector is shrouded by warp storms, preventing further investigation. Declared Perdita by the Inquisition.

Devlan: (Ultima Segmentum) Imperial Mining world consumed by Hive Fleet Kraken 997.M41. The extensive system of Sentinel space stations around Devlan delayed the hive fleet long enough for a fleet of giant freighters to escape into space. A company of the Lamenters Space Marines held off frenzied attacks by the Tyranids until the last ship was loaded. Left surrounded and cut off, the Lamenters commended their souls to the Emperor and took a heavy toll of the invaders before they were finally overrun.

Dimmamar: (Segmentum Obscurus) Confederation of Light founded on Dimmamar c.M33, which professed a penitent faith that believed the sacrifice of the Emperor should serve as an example to everyone. Their ideas of poverty and humble living directly contradicted the the teachings of the Ecclesiarchy and was declared a heretic assembly ans driven to virtual extinction. Dimmamar was also the birthplace of Sebastian Thor, 292nd Ecclesiarch. Thor was a revolutionary preacher during the Age of Apostasy who led a rebellion against the treacherous High Lord Vandire and eventually became the Ecclesiarch, Thor I. Thor initiated the reforms that would eventually lead to the Reformation of the Ecclesiarchy.

Dorn: (Segmentum Solar) Imperial outpost, possibly destroyed by invading Orks during the Ryza campaign.

Dregruk: (Segmentum Obscurus) Ork homeworld of the Great Despot of Dregruk, whose Waaagh overran at least five Imperial worlds between 450-996.M41. The Great Despot Gazgrim participated in the Third War for Armageddon.

Dulma'lin: (Segmentum Solar) Imperial world. Raised recruits for the Ryza campaign.

Earth: (Segmentum Solar) Also known as Terra or Holy Terra, Earth is the seat of the Emperor of Mankind, interred in the "Golden Throne." It is the home of most Imperial offices and includes the vast Adeptus Mechanicus offices and factories of Mars and the Grey Knights Space Marine base on Titan, one of Saturn's moons.

El Phanor: (Segmentum Solar) The Citadel of Kromarch on El Phanor fell to Abaddon the Despoiler leading to the devastation of the entire planet during a Black Crusade.

Epsion Octarius: (Segmentum Tempestus) Ork homeworld of the Over Fiend of Octarius whose Waaagh overran at least five Imperial worlds between 450-996.M41. During the jungle wars on Epsion Octarius, a Catachan regiment survived for nearly forty days amidst Crotalid infested mangrove swamps before reaching the Ork Gargant construction site of Grubnak's Drops. The savagery of the Catachans so impressed the Ork Warlord that he ordered his Gargants to be painted in green jungle stripes with red bandanas, in imitation of the Jungle Fighter's uniforms. Tyranid Hive Fleet Leviathan centered its invasion in 997.M41 around Octarius Epsion.

Espandor: (Ultima Segmentum) Forest world of Ultramar consumed by Hive Fleet Kraken in the Second Tyrannic War 997.M41. Espandor was settled during the Age of Strife by traders blown off-course and subsequently stranded by warp storms. It was the least densely populated of all the worlds of Ultramar.

Eye of Terror: (Segmentum Obscurus) The largest Warp Space-Real Space interface in the galaxy, the Eye of Terror was created by the birth of the Chaos God, Slaanesh. The Eldar are said to be responsible for this catastrophe through their unparalleled psychic indulgences and suffered the loss of most of their civilization as a result of the destruction wrought by the creation of Slaanesh and the Eye of Terror. The remnants of the Traitor Legions fled to the Eye of Terror after the Horus Heresy.

Estaban 3 and 7
Ultima Segmentum. Located near to the Storm of the Emperor’s Wrath. Two Forgeworlds located in the Estaban system. They are both large and important forgeworlds and serve as a base to the Legio Tempestor and Legio Magna Titan Legions Respectively

Eustis Majoris Segmentum Obscuras. The current “capital” planet of the Helican Subsector.

Evoria (my own system) Segmentum Ultima. Situated on the eastern fringe of the galaxy. This system is believed by the Adeptus Mechanicus to have been artificially created in an age before humans existed. Discovered and claimed in the name of the Emperor during the Great Crusade. The system is unique in that it has ‘shell’ of asteroids that severely limit movement of vessels into and out of the system. This system has been attacked by large Chaos fleets on no less than four occasions, each of which were repelled thanks to the defensive properties of the asteroid shell. It has also come under attack by Tyranids, which were eventually driven off with the assistance of the Angels of Fury Space Marine Chapter. A mainly martial society, whose primary tithe to the Imperium is Imperial Guard regiments. Is home to a small order of the Sisters of Battle. The dominant predator on the planet is the “Serrator”; a large reptilian carnivore whose primary prey is the free-roaming Larnal. The planet’s Stormtrooper equivalent are named “Serrators” in honour of the lethality and ferocity of this animal.

Fenris: (Segmentum Obscurus) Homeworld of the Space Wolves Space Marine chapter. Planet of "Fire and Ice," the planet's vast ocean freezes over completely for half the year. The thaw occurs when the planet's pronounced eliptical orbit approaches its sun, when the planet's surface is subjected to searing heat, triggering vulcanic and tectonic activity due to the increased gravitational forces of the sun. The only stable land mass is the small continent, Asaheim, where the Space Wolves have built their fortress within the bowels of the highest peak, which they call "The Fang." During the "Plague of Disbelief," Fenris was beseiged by the Apostate Cardinal Bucharis, but a counter-attack by Kyrl Grimblood's Great Company successfully lifted the siege and Fenris was never taken. According to a theory by the respected Magos Biologis Anatole Leviticus, Fenris may have possibly been unsuccessfully invaded by Tyranids in the past, due to the presence of the "kraken" (terrifying tentacled leviathans) that haunt the seas of Fenris.

Formund: (Ultima Segmentum) Imperial Ogryn world. Homeworld of the Ogryn hero Nork Deddog, where he returned to live in retirement as chief of his people at the age of 110.
Gathalamor: (Segmentum Solar) Imperial world. Diocese of the Apostate Cardinal Bucharis, who, after enslaving the population of Gathalamor, led a reign of terror called the "Plague of Disbelief" which encompassed a great crescent of planet systems spreading from Gathalamor north and west up to and including the Imperial Navy base of Hydraphur, northeast to besiege Fenris, and south to the gates of the Imperial Navy base at Bakka. Two events were to prove disatrous to the Cardinal's aspirations to rule the Imperium: the unsuccessful siege of Fenris and the preachings of Confessor Dolan from Chiros, who instilled rebellion against the Cardinal's regime wherever he travelled. Upon the announcement of Confessor Dolan's death on Gathalmor (after a public trial which allowed Dolan to deliver a three day speech), Bucharis' palace was stormed by a popular uprising, and Bucharis was literally torn limb from limb by the angry mob as he attempted to escape the planet by space shuttle.

Gathrog: (Segmentum Obscurus) Ork homeworld of the Arch Dictator of Gathrog, whose Waaagh overran at least five Imperial worlds between 450-996.M41.
Gorkamorka (aka Angelis): (Ultima Segmentum) An isolated Ork World inhabited by rival mobs of Orks whose space hulk crash-landed on Angelis, a planet under Imperial exploration. The small human population was all but eliminated by the catastrophic crash of the space hulk. The surviving Orks, driven by instinct, began to build their "Gorkamorka" spaceship which they hoped would some day lead them back to the stars to conquer the galaxy in a great, final Waaagh. Unfortunately for the Orks, rivalries soon broke out which slowed the construction of the great Gorkamorka due to incessant battles for resources and supremacy. Other races thought to exist on Gorkamorka include mutated humans (Muties), tribal humans (Diggas), and presumed Necrontyr. Gorkamorka is the setting for the game by the same name.

Graia: (Ultima Segmentum) Imperial Factory world infested with Genestealers and subsequently attacked by Tyranids during the Second Tyrannic War 997.M41 (Hive Fleet Kraken), but was sucessfully defended and cleansed.

Gryphonne IV: (Ultima Segmentum) Adeptus Mechanicus Forge world, home to the War Griffons Titan Legion. Involved in the Tyranid Hive Fleet Leviathan invasion of 997.M41.

Gudrun Segmentum Obscuras. A peaceful world, which features many stately mansions and small villages situated amongst rolling hills. The Radical Inquisitor Gregor Eisenhorn used a mansion on the world as a home and HQ for a short while.

Guryan: (Segmentum Pacificus) Mining world which was the second planet system to successfully revolt against the Apostate Cardinal Bucharis' regime, driven to rebellion by the preachings of Confessor Dolan.

Helios Segmentum Unknown. World upon which the Red Scorpions Space Marine chapter first fielded the “Helios” pattern Land Raider.

Hydraphur: (Segmentum Pacificus) Segmentum Pacificus Imperial Naval Base.

Iax: (Ultima Segmentum) Agri-world of Ultramar. Iax is sometimes called the Garden of Ultramar. Its climate and fertility have made it one of the most naturally productive worlds in the Imperium. There are no large cities on Iax. The oldest and most densely urbanized area on Iax is the ancient fortress city of First Landing, whose tall citadel has withstood the barrages of invaders over the centuries.

Ichar IV: (Ultima Segmentum) Imperial Hive world infested by Genestealers and invaded by Tyranids in the Second Tyrannic War (Hive Fleet Kraken). Ultramarines led by Marneus Calgar in cooperation with Imperial Guard forces and Iyanden Eldar defeat the Tyranids and cleanse the planet of Genestealers. Marneus Calgar was presumably killed in the action.
Iyanden: (Ultima Segmentum) Eldar Craftworld decimated by Tyranid attacks during the Second Tyrannic War 997.M41 (Hive Fleet Kraken). The Iyanden Ghost Warriors are so named due to the craftworld's reliance on "Wraith-guardians" to bolster their ranks in battle.

Jagga: (Ultima Segmentum) Ork homeworld of the Great Tyrant of Jagga, whose Waaagh overran at least five Imperial worlds between 450-996.M41.

Jakart: (Segmentum Pacificus) Ork world conquered by Lord Solar Macharius. During an assault against an Ork-held fort, Macharius received debilitating wounds from the Ork Warboss defending the place, who Macharius personally killed along with a dozen other Orks. The wounds were to haunt him for the rest of his life.

Jhanna: (Ultima Segmentum) Imperial planet attacked by High Lord Vandire's "Reign of Blood" during the Age of Apostasy. Vandire used the planet's orbital batteries to melt Jhanna's polar ice caps, drowning nearly 4 billion people in the resulting flood. Later, in 807.M41, Marneus Calgar leads forces that recapture two Ocean cities (Omon and Vorlencia) from Chaos Space Marines.

Jucha: (Segmentum Pacificus) Jungle world where Lord Solar Macharius contracted a fatal fever while fighting there.

Jurn: (Segmentum Tempestus) Ork homeworld. Site of battle involving an Imperial Guard Valhallan regiment in which Captain Chenkov of Valhalla held an isolated prepared position against a vast Ork horde for three days until relief forces could arrive. Of the 600 men involved in the action, only 63 survived the battle.

Kar Duniash: (Ultima Segmentum) Imperial Segmentum Naval Base for Ultima Segmentum.

Kato: (Segmentum Solar) Imperial Outpost.

Kallastin: (Segmentum Pacificus) Planet held by mutant human rebels conquered by Lord Solar Macharius. During the fighting for the planet, the 3rd Tallarn regiment earned their nickname, the "Tallarn Desert Tigers," and received a commendation from the Inquisition.

Kimmeria: (Ultima Segmentum) Feral World involved in the Tyranid Hive Fleet Kraken invasion 997.M41.

Konor: (Ultima Segmentum) Adeptus Mechanicus Research world.

Lamarno: (Ultima Segmentum) Feral planet consumed by the Tyranids during the invasion of Hive Fleet Kraken in 997.M41.

Lastrati: (Ultima Segmentum) Imperial Hive world. During the Age of Apostasy, the ruthless Divine Army sect gains control and enslaves and/or kills all but 2.5 million of the planet's population of 14 billion.

Lochhelion VI: An Imperial mining world that is completely covered in poisonous gases. The only hospitable areas are inside the mountain tops. This is also the homeworld of the Hawk Lords Space Marine chapter.

Loquit Segmentum Obscuras. Homeworld of the Q’orl; an insect like race with a small empire located relatively near to the Eye of Terror. The Q’orl have a caste-based society, reminiscent of a swarm of wasps, with a single queen at the head, tended to by a huge swarm of her offspring. They have been noted to have dealings with the Eldar in the past, but now consider them untrustworthy after the Eldar(possibly Dark Eldar) kidnapped one of the Q’orl hive queens.

Luther McIntyre IX: (Segmentum Tempestus) Desert World. Home to the Ambull, Crawler, Sunworm, Micah Dragon, and other foul creatures. At least one Imperial Guard regiment has been recruited from Luther McIntyre; Commissar Yarrick served with them during his career.
Macharius: (Segmentum Pacificus) Imperial planet where Lord Solar Macharius launched his campaign of conquest and used as a supply base during the campaign. Upon his death, Macharius' body was returned to and entombed on the planet, renamed "Macharia" in honor of the great hero.

Mackan: (Segmentum Solar) Imperial world which was the scene of an epic battle between the Blood Angels and Khorne Berserkers led by Abaddon the Despoiler.

Macragge: (Ultima Segmentum) Homeworld of the Ultramarines Space Marine chapter. Macragge is a bleak and rocky planet, with over 75% of its land mass bleak mountainous upland which is almost entirely devoid of life. The people live in fortresses built and maintained by the Ultramarines. The Fortress of Hera holds the Shrine of the Primarch, where Roboutte Guilliman is entombed on a huge ornate marble throne protected by a stsis field which prevents the decay of his body. Macragge was invaded by Hive Fleet Behemoth in the First Tyrannic War in 745.M41, a combined force of Ultramarines, Ultramar Auxillaries, titans from the Legio Praetor, and a battlefleet from Bakka successfully defended and virtually destroyed the invading fleet. During the fighting, the Ultramarine elite 1st Company was completely anihilated.

Maelstrom: (Ultima Segmentum) A large Real Space-Warp Space interface near the Galactic Core. The warp storm is home to Chaos renegades that use the region as a staging area from whence they raid nearby systems. The most notorius of these raiders is the Tyrant of Badab, Huron Blackheart of the renegade Astral Claws Space Marines.

Masali: (Ultima Segmentum) Agri-world of Ultramar. The planet is actually an arid desert world, but the inhabitants have constructed gigantic domed horticultural cities that cover hundreds of square miles, capturing precious water in wind traps and storing it in massive underground tanks. Tarentus and Quintarn have used the same technique, and all three planets are collectively known as the "Three Planets." In 759.M41, Marneus Calgar led forces which drove out Ork scavengers who had captured the Three Planets in the aftermath of Hivefleet Behemoth.

Medrengard Segmentum Obscuras. A daemon world, located within the Eye of Terror, currently occupied by the dread legions of the Iron Warriors. Theorised to be the location of Purturabo, the primarch of the Iron Warriors. The surface of the planet is primarily made up of chipped rock and waste materials from the planet’s vast and numerous weapon factories. The sky of the world is a featureless white expanse with a single black sun. The world also has extensive prison facilities in which the Iron warriors keep the many captives they take whilst fighting.

Methalor: (Segmentum Solar) Hive world which successfully rebelled against the Apostate Cardinal Bucharis' control. Enraged by "righteous indignation" instilled by Confessor Dolan, the population of its principle hive self-immolated themselves in a raging inferno caused by overloading the hive's geo-thermal power grid.
Miral: (Ultima Segmentum) Jungle Deathworld invaded by Tyranids during the Second Tyrannic War (Hive Fleet Kraken) 997.M41. The planet was defended by the Emperor's Scythes Space Marines and the Imperial Guard, but the planet was overrun and consumed by the Tyranids.

Moloch: (Ultima Segmentum) Imperial Mining world attacked by Tyranids in the Second Tyrannic War 997.M41 (Hive Fleet Kraken).

Molov: (Ultima Segmentum) Imperial planet made famous by Redemptor Kyrinov's independent handling of the Molovian Heresy where he led a popular revolt against the renegade Governor of Molov, Governor Vlachek.

Mordian: (Segmentum Obscurus) Imperial Hive World - the World of Eternal Night. Home world of the Mordian Iron Guard.

Necromunda: (Segmentum Solar) Imperial Hive world. Imperial Guard recruitment world. Imperial Fists Space Marines win a battle against Orks in the ash wastes, establish a Fortress-Chapel, and recruit on Necromunda. Site of undercity hive gang warfare of Games Workshop's game of the same name.

New Hope: (Ultima Segmentum) Imperial Frontier world involved in the Tyranid Hive Fleet Leviathan invasion in 997.M41.

Okassis: (Ultima Segmentum) Cardinal world. Saint Praxedes of Ophelia VII, Cannoness of the Order of Our Martyred Lady, reinforced the Calaenian Imperial Guard on Okassis during a Tyranid incursion during the Second Tyrannic War. The Tyranid invasion was stalled, allowing refugees time to evacuate the stricken planet. As she fought deeper within the ranks of the Tyranid army, all contact was lost with her and her army. She became the first Martyr to the Kraken.

Ophelia VII: (Segmentum Tempestus) Imperial world. Site of the Ecclesiarchal Synod-Ministra and the Adepta Sororitas Convent Sanctorum. Ecclesiarch Benedin IV moved the Holy Synod and the upper echelons of the Adeptus Ministorum from Terra to the rich planet of Ophelia VII in an attempt to limit the power of the High Lord of the Administratum. The Ecclesiarchal palaces on Ophelia cover nearly 90,000 square miles and soar 4,000 meters into the sky.

Ornsworld: (Segmentum Obscurus) Imperial Ratling homeworld. Invasion in M41 at the beginning of the Gothic War by Chaos forces resulted in the capture of the "Eye of Night" artifact.

Paramar V: (Segmentum Obscurus) Imperial Hive world devastated by titan legions (Deaths Heads Chaos Space Marines and Chaos Legio Mortis titan legion vs. Imperial Legio Ignatium titan legion). Fabius Bile known to surviving scattered tribes as the "Clonelord."
Parmenio: (Ultima Segmentum) Ultramarines training world in Ultramar.

Piscina IV: (Segmentum Obscurus) Oceanic world. Imperial outpost invaded by Ork forces led by Warlords Ghazghkull Thraka and Nazdreg. The invasion was thwarted by the Dark Angels. Piscina V is a desert and jungle world, colonized prior to the Dark Age of Technology.
Planet of the Dead: (Ultima Segmentum) Dead world invaded by Tyranids during the Second Tyrannic War 997.M41 (Hive Fleet Kraken).

Port Maw: (Segmentum Obscurus) Hive World. Gothic Sector Naval Base. The Main space port in the Gothic Sector. The shipyards of Port Maw played a large part in keeping the fleets of the Gothic Sector running during the Gothic War. However, the system was blockaded by the fleets of Chaos – unwilling to risk a direct attack on the system thanks to its vast array of system defences and intra-system defence vessels.

Posul: (Segmentum Tempestus) Night world, shrouded in near perpetual darkness.
Homeworld of the Mortifactors Space Marine chapter. Inhabited by fierce nomadic tribes, who are in constant warfare with each other. The tribesmen, from whom the Mortifactors recruit, are known to eat the flesh of their slain enemies, ritually gaining the strength and skill of the fallen foe.

Prandium: (Ultima Segmentum) Civilized world of Ultramar consumed by Hive Fleet Behemoth 745.M41. Prandium was once a world teeming with life, originally settled by colonists from Macragge after the Horus Heresy. The planet soon became the most beautiful jewel of Ultramar and prospered until its destruction and consumption by the Tyranids. It is now dead and lifeless, its even its atmosphere consumed by the Tyranid attack.

Prospero: (Segmentum Solar) Homeworld of the Thousand Sons. Cleansed during the Horus Heresy by Leman Russ and the Space Wolves.

Purgatory: (Segmentum Obscurus) Imperial mining outpost. Site of a battle involving Cadian Imperial Guardsmen and the Night Lords in which the Night Lords capture the "Hand of Darkness" artifact.

Quintarn: (Ultima Segmentum) Agri-world of Ultramar. The planet is actually an arid desert world, but the inhabitants have constructed gigantic domed horticultural cities that cover hundreds of square miles, capturing precious water in wind traps and storing it in massive underground tanks. Tarentus and Masali have used the same technique, and all three planets are collectively known as the "Three Planets." In 759.M41, Marneus Calgar led forces which drove out Ork scavengers who had captured the Three Planets in the aftermath of Hivefleet Behemoth.

Quisto'Rol: (Ultima Segmentum) Human world near the Storm of the Emperor's Wrath.
Radnar: (Ultima Segmentum) Imperial Hive world, infested with Genestealers during the Second Tyrannic War (Hive Fleet Kraken).

Rhanna: (Segmentum Solar) Imperial Mining world. Conquered by the Apostate Cardinal Bucharis where he joined forces with the renegade Navy Admiral Sehalla and a colonel of the Rigellian XXV Imperial Guard regiment. With these forces, he began his infamous "Plague of Unbelief" campaign of terror throughout the Imperium.

Rigant: (Ultima Segmentum) Agri-world involved in the Tyranid Hive Fleet Leviathan invasion in 997.M41.

Ryza: (Segmentum Solar) Imperial Adeptus Mechanicus Forge world. Successfully defended against an Ork Waaagh with aid from surrounding systems.

Salem: (Ultima Segmentum) Ecclesiarchy Monastery world consumed by Hive Fleet Kraken 997.M41. The monks living on the giant asteroid-monastery chose to poison themselves and their carefully built ecosystem rather than allow their sanctified flesh and bones to be consumed by the Tyranids.

San Leor: (Ultima Segmentum) Agri-world, homeworld of the "Daughters of the Emperor" sect, whose membership did not exceed 500 women. During the Age of Apostasy High Lord Vandire "adopted" the Daughters of the Emperor and renamed them the Brides of the Emperor, using them as his praetorian guard (elite bodyguards). After the fall of Vandire and the enactment of the Decree Passive, prohibiting the Ecclesiarchy from maintaining a force of "men under arms," Ecclesiarch Thor I (Sebastian Thor) adopts the Daughters of the Emperor as an elite militant Ecclesiarchy force, thus establishing the Orders Militant of the Adepta Sororitas (Sisters of Battle) and bypassing the prohibition of an Ecclesiarchal armed force.

Solstice: (Segmentum Tempestus) Feudal Ice world. During a missionary visit to Solstice, Uriah Jacobus, Protector of the Faith, began his mission to introduce the doctrines of the Ecclesiarchy into the natives' own disorganized religion. Discovering a Genestealer cult, he led forces armed with nothing more than crossbowmen and cavalry armed with swords and lances against the Genestealers in the Battle of Solstice. After his victory, Jacobus became a legendary figure and during his lifetime, converted twenty-two worlds to the Imperial Creed in Segmentum Tempestus before dying on the death world of Gorang from a lung-destroying virus.

Sotha: (Ultima Segmentum) Homeworld of the Emperor's Scythes Space Marine chapter, consumed by the Tyranid Hive Fleet Kraken during the Second Tyrannic War 997.M41.
St. Capilene: (Ultima Segmentum) Ecclesiarchal Missionary world destroyed by the Tyranid Hive Fleet Leviathan invasion of 997.M41.

Stygies VIII: (Segmentum Obscurus) Imperial Adeptus Mechanicus Forgeworld moon of a gas giant in the Vulcanis system. Known for its production of many Imperial Guard tank variants.

The Storm of the Emperor's Wrath: (Ultima Segmentum) Large warp storm that appeared in the Clax system during the Age of Apostasy that destroyed an entire war fleet sent by the treacherous High Lord Vandire to raze Dimmamar.

Sulairn: (Segmentum Solar) Ork Homeworld.

Talasa Prime: (Ultima Segmentum) Inquisition Fortress world. Inquisitor Kryptman presumably launched his Inquisitional Inquiry from Talasa Prime in his quest to investigate the cause of the destruction of worlds eventually identified as the Tyranids.

Talassar: (Ultima Segmentum) Ocean world of Ultramar. Talassar is a planet of storm-tossed seas and rocky islands, with a single continent known as Glaudor, which was the site of a major battle between the Ultramarines and invading Orks immediately after the Horus Heresy.

Tallarn: (Segmentum Tempestus) Imperial desert world. Homeworld of the Tallarn Desert Raiders. The world of Tallarn was once a fertile planet bathed in the light of its twin suns. Oceans, plains, and lush jungles covered its surface, and its people prospered until invaded by the Iron Warriors Chaos Space Marines during the Horus Heresy who virus bombed the planet. The Tallarn that could, hid in enviro-shelters deep beneath the planet's surface. In seven weeks they emerged to find a desolated world under the control of the Iron Warriors. The resulting Battle of Tallarn raged for many months and was the largest armored conflict of the Horus Heresy. The Iron Warriors were eventually driven from the planet, but Tallarn was left a putrid wasteland littered with the wreckage of more than a million shattered vehicles.

Tanith Segmentum Pacificus. Homeworld of the Tanith First-and-Only IG Regiment. A largely temperate world with vast amounts of land covered by Nalwood forests. Nalwood trees were unique in that they are capable of movement, meaning the forests on Tanith never remain the same. This led to the populace developing an excellent sense of direction, as they could not rely on paths through the forests that disappeared as quickly as they were formed. The capital city of the planet was known as Tanith Magna and was governed by someone called the Elector. Tanith was split into several provinces, each containing a “bastion” city. Its inhabitants had a culture that is often likened to that of the Scottish highlanders, many sported blue tattoos. The woodsmen of Tanith were called the Nalsheen, and possessed a unique form of martial arts called cwlwhl. A common curse on the planet was the word “Feth”. A Chaos fleet destroyed the planet during the Sabbat Worlds crusade, the only survivors being members of the First-and-Only Regiment under the command of Colonel-Commissar Ibram Gaunt.

Tarentus: (Ultima Segmentum) Agri-world of Ultramar. The planet is actually an arid desert world, but the inhabitants have constructed gigantic domed horticultural cities that cover hundreds of square miles, capturing precious water in wind traps and storing it in massive underground tanks. Quintarn and Masali have used the same technique, and all three planets are collectively known as the "Three Planets." In 759.M41, Marneus Calgar led forces which drove out Ork scavengers who had captured the Three Planets in the aftermath of Hivefleet Behemoth.

Taros III - Ultima Segmentum. The only inhabitable planet in the Taros system, located uncomfortably close to the borders of the Tau Empire. A desert world whose chief exports include metals mined form the plant's crust. In the 38th millennium, the Adeptus Mechanicus noticed discrepancies in the planetary tithe payments from Taros. Further investigation revealed the Planetary Governor was trading with the Tau. An attempt by the Avenging Sons Space Marine Chapter to remove the governor was thwarted by a Tau Hunter Cadre. A ground campaign followed (including several regiments of Imperial Guard from Cadia, Elysia and Tallarn, a Scout Titan Battlegroup form Legio Ignatum and two companies of the Raptors Space Marine Chapter) from which the Tau emerged victorious. They have been the Rulers of Taros ever since.

T'au: (Ultima Segmentum) Homeworld of the Tau and capital planet of the T'au empire. First discovered six thousand years ago, the Tau have advanced since that time from a barbaric feral race to a highly technical society capable of Warp travel. The Tau Empire spans 300 light years and includes an allied race called the Kroot who they employ as mercenaries.

Tesla Prime: (Ultima Segmentum) Adeptus Mechanicus weapons testing planet, destroyed in the Tyranid Hive Fleet Leviathan invasion of 997.M41.

Thoth: (Segmentum Pacificus) Desert World. Liberated by Lord Solar Macharius from Chaos-worshipers. Captain Al'Rahem of Tallarn led the indigenous N'go tribesmen and conducted a guerrilla campaign against the Chaos-tainted Thoth, winning him fame throughout Macharius' army. The Inquisition subsequently declared Thoth "Amundi Heretica" and cleansed the world with virus bombs. The N'go were evacuated to other Imperial worlds along with genetic samples of the other indigenous fauna and flora.

Thandros: (Ultima Segmentum) Mining system with an Imperial System Telepathica Matrix, consumed by the Tyranid Hive Fleet Behemoth 745.M41. Telepathica matrices boost psychic Astropath signals for intragalactic communication. Inquisitor Kryptman attempted to send a priority warning to the Imperium through the Matrix concerning the invasion of the Tyran system, but was unable to get the message through. When he arrived in the Thandros system, the planets had already been overrun.

Thracian Primaris Segmentum Obscuras. A Hiveworld, formerly the “capital” planet of the Helican subsector. After a massacre, masterminded by the rouge Inquisitor Quixos, occurred on the planet it fell behind to another planet in the area, known as Eustis Majoris. During the Massacre, Inquisitor (then Interrogator) Ravenor was horrifically injured and forced to remain in a life support chair for the rest of his life.

Thranx: (Segmentum Solar) Imperial Hive world. Site of conflict during the Great Crusades (Space Wolves) and the Horus Heresy. Thranx was eventually virus bombed by the Dark Angels after being taken over by Genestealers.

Tigrus Ultima Segmentum. Was an important Forgeworld. Original developer of the Vanquisher cannon. Was invaded and overrun by Orks in M.35. Since the loss of this Forgeworld the availability of the LR Vanquisher variant has dropped significantly. Is still ruled by the Orks.

Tirathain: (Ultima Segmentum) Eldar Exodite world involved in the Tyranid Hive Fleet Leviathan invasion of 997.M41.

Triplex Phall: (Ultima Segmentum) Adeptus Mechanicus Forge world involved in the Second Tyrannic War 997.M41 (Hive Fleet Kraken).

Tyran: (Ultima Segmentum) Ocean world. Adeptus Mechanicus Explorator base. First known encounter with the Tyranid race, from whence they are named. The oceans of Tyran covered 80% of the world's surface. The planet was consumed by Hive Fleet Behemoth in 745.M41. No warning could be given to the Imperium due to the warp disturbances caused by the Hive Fleet. Inquisitor Kryptman reaches Tyran over a year later and realizes the great threat posed to the Imperium. He later travels to Thandros, salvages the damaged Telepathica Matrix and broadcasts a message warning of the approaching apocalypse.

Ulani: (Segmentum Solar) Imperial world. Raised recruits for the Ryza Campaign.

Ulthwe: (Segmentum Obscurus) Eldar Craftworld close to the Eye of Terror. The name is a contraction of 'Ulthanash Shelwe' (Song of Eldanash). Led by Eldrad Ulthran.

Ultima Macharia: (The Halo Zone beyond the edge of the Astronomicon, Segmentum
Pacificus) The furthest world reached by the conquests of Lord Solar Macharius.

Umoja - Umoja System - Segmentum Ultima : A temperate, serene world known for it's many waterfalls and odd gravitational fields. Capital World of The Umoja system, it’s often used as an "out of the way" resort by politicians and wealthy merchants. Umoja has one moon, Danika. The Broken Wings chapter of the Adeptus Astartes is based here. Their fortress monastery "The Cathedral" dominates the entire southern pole of the swamp covered moon.The planet and it's moon where over-run by Chaos forces in the Umoja Incident of M41.999 and abandoned.

Grueza - Umoja System - Segmentum Ultima : Grueza is the smallest planet in the Umoja system and the farthest from the systems two suns. Grueza is a frozen mountainous planet wracked by almost constant ice storms. Home to a few nearly abandoned Imperial research stations; it's a haven for criminals and drifters. It's rumoured that the Dark Eldar Kabal of the Shattered Soul has a base somewhere in the Ice Caverns beneath the planet's surface. All contact was lost with the planet during the Umoja incident of M41.999.

Harnella - Umoja System - Segmentum Ultima : Harnella marks the point were two major Imperial shipping lanes converge. Harnella had prospered greatly from the constant stream of merchant ships that passed through the massive ring-shaped Port Harnella shipyard that orbited the planet. Harnellas orbit is scattered with dozens of small asteroids and satellites equipped to handle the overflow from the busy shipping yards. The rest of the system sustained itself on the funds generated by the Port Harnella yards.Harnella was completely destroyed in the Umoja Incident of M41.999

Kelmora - Umoja System - Segmentum Ultima : Kelmora was a world almost completely dedicated to feeding the rest of the Imperium. Almost 90% of the planet's landmass, 60% of the planet's total surface was dedicated to farming, the rest mostly water storage and small clusters of administrative complexes. Large shipments of food where shipped from its massive greenhouse complexes and used to feed the other planets in the system. The large surplus was then sent to Harnella were it was divided up and dispersed throughout the Imperium.Kelmora supplied almost all the food for the Umoja system and a few of the surrounding systems.Kelmora was stripped of all life and made uninhabitable in M41.999 by invading Chaos forces.

Berthe - Umoja Umoja System - Segmentum Ultima : Centuries ago Berthe was caught in a religious civil war. The planet was ruled by two cardinals, each of them having different ideas of what the Emperor’s will was. The war was eventually ended when the Adeptus Sororitas "Order of the Red Star" intervened, but the result of the conflict is still present on Berthe.The cardinals competed with each other to see who could build the greatest monument to the Emperor’s glory. The cities of Berthe are crowded with Grande Cathedrals; each one more extravagantly decorated then the last. The cities of Berthe are a mecha for Imperial cult; millions of pilgrims pass through every day to marvel at the massive cathedrals and extravagant monuments. Berthe has two moons. Fellana, a small moon covered by deep forests, is home to a small shrine of the Order of the Steel Rose, and Demundza, a small volcanic moon that acts as a miniature forge world, with Adeptus Mechanicus factories set up in the hearts of active volcanoes to help supply the system's military.Berthe and it's moons where captured by Chaos forces in M41.999. Berthe is the only planet in the system on which small pockets of Imperial resistence still exist.

Zoshonel - Umoja System - Segmentum Ultima :The closets planet to the Umoja system's duel suns,Zoshonel is an arid desert planet.Few things can survive the harsh Zoshonel days,and most of the native life forms live in the network of underground caves that run under the planet's surface.Human habitation is limited to a few small mining colonies that harvest the mineral deposits deep beneath the planet's crust.Zoshonel was the first planet lost to Chaos forces in M41.999 and it's believed an artefact buried underneath the planet's surface is what lead the ruinous powers to the system in the first place. All contact with the planet has been lost and the fate of it and it's inhabitants are unknown.

Urdesh Segmentum Pacificus. This Forgeworld was the primary supplier of arms to the imperial forces participating in the Sabbat crusades.

Uralan: (Segmentum Obscurus) Imperial world destroyed by Abaddon the Despoiler in his first Black Crusade after the Horus Heresy. During the invasion, Abaddon recovered the daemon sword, Drach'Nyen in the crypts beneath the Tower of Silence.

Vacuna: (Ultima Segmentum) Ork homeworld of the Grand Warlord of Vacuna, whose Waaagh overran at least five Imperial worlds between 450-996.M41.

Valedor: (Segmentum Tempestus) Imperial Cathedral world, involved in the Tyranid Hive Fleet Leviathan invasion in 997.M41.

Valhalla: (Ultima Segmentum) Imperial planet, Ice world. Homeworld of the Valhallan Ice Warriors. Valhalla was once a temperate paradise of forests and broad fertile plains, until it was hit by a comet which knocked the planet from its orbit, causing catastrophic climate changes. To add to their woes, the Valhallans were subsequently invaded by Orks, which after a prolonged war, were finally defeated by the stalwart defenders.

Valos: (Ultima Segmentum) Barren world likely attacked by the Tyranid Hive Fleet Behemoth prior to its subsequent overrunning of Tyran.

Vanaheim: (Segmentum Solar) Imperial Hive world. Site of terrible slaughter during the Horus Heresy (three hives were massacred, the Iron Warriors were known to be present).

Vengeance: (Ultima Segmentum) Overrun by Tyranids before Lord Alberan Varn could invade it himself. Varn's would-be invasion fleet lost 107 years in the warp due to a warp anomaly; when he finally emerged, Vengeance was a smoldering Tyranid-infested ruin. Nevertheless, Varn continued his attack, declaring, "I've travelled a thousand stars and a hundred years to conquer this damned planet, and conquer it I will!".

Veridian: (Ultima Segmentum) Jungle world attacked by Tyranids in the Second Tyrannic War (Hive FLeet Kraken) 997.M41, defended by Catachan Imperial Guard.

Voss Prime Segmentum Solar. This Forgeworld is home to the Legio Invigilata Titan Legion. It is an extremely important Forgeworld, being the closest Forgeworld to the Armageddon system. Despite its relative importance, this Forgeworld lacks the understanding and manufacture facilities to make plasma reactor technology.

V'run: (Segmentum Tempestus) Ork homeworld. Commissar Yarrick learns the Ork tongue while fighting on V'run early in his career.

Yarant: (Segmentum Solar) Imperial world. Abbadon the Despoiler led the Sons of Horus terminators in a campaign against Yarant Loyalists during the Horus Heresy.