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Mass Effect Wiki
See also: Races

The Milky Way and Andromeda galaxies have existed for several billion years. In that time, countless races have attained sentience, forged civilizations, explored the depths of space, and then become extinct. These background races are often barely understood by the contemporary civilizations, who have pieced together scant details of a mere handful of ancient races through ruins and artifacts.

Identified Milky Way Races


The arthenn flourished across multiple worlds in the Zelene system some 300,000 years ago. Their homeworld appears to have been Helyme, a dead planet where all complex life was wiped out in an unknown cataclysm. The third planet in the system, Epho, was mined or otherwise settled before these settlements were wiped out by kinetic impacts. The system's outer gas giant, Gaelon, was the location of a complex helium-3 mining infrastructure. Material debris suggests arthenni technology was equal to the current galactic state-of-the-art.


The densorin were a race that existed at the time of the Protheans. At some point, they fought a war against the oravores. When the Reapers invaded the galaxy, the densorin attempted to pacify them by sacrificing their children to them, but this only allowed the Reapers to destroy the densorin more quickly. The densorin are known to have studied celestial mechanics and morphological simulations of galactic language, topics beyond the understanding of even the Protheans.


The inusannon were a spacefaring race that existed at least 127,000 years ago. Little is known about them except that they warred with another race, the thoi'han, over colonization rights to the garden world Eingana, and that they inhabited Ilos at some point. The inusannon were eventually wiped out by the Reapers. Tens of thousands of years later, the ruins of inusannon civilization provided the Protheans with the knowledge necessary to develop mass effect technology.


The oravores were a spacefaring race that existed at the time of the Protheans. When they attacked the asari homeworld of Thessia to gain control of its vast resources, the Protheans stopped them. This event would later be remembered in asari mythology as when the goddess Athame wielded her sword against jealous gods who threatened the asari. The oravores also fought a war against the densorin.


Little is known about the thoi'han except that they warred with the inusannon over colonization rights to the garden world Eingana 127,000 years ago. The wreckage of starships from both races litter the planet.


The zeioph were an ancient spacefaring race that built millions of elaborate crypts on the surface of the planet Armeni. Archaeological excavations of these crypts have been prohibited by the Citadel Council law, which holds grave sites as sacrosanct.


The zha'til were a synthetic race that existed at the time of the Protheans. They originated when a race known as the zha implanted themselves with symbiotic AI technology to enhance their intelligence in order to survive as their homeworld became inhospitable. When the Reapers arrived, they subjugated the AIs, known as zha'til, who then seized control of the bodies of their masters and altered their genetic material at the deepest level, transforming the zha into synthetic monsters and their offspring into slaves. The zha'til proceeded to multiply into "mechanical swarms" that "blotted out the sky". With no other recourse, the Protheans sent the star of the zha's home system into supernova, destroying the zha'til entirely.

Other Identified Races

The Prothean Javik briefly mentions several other spacefaring races who existed at the time of the Prothean Empire 50,000 years ago.

  • Ditakur - The aggressive ditakur wiped out the synril.
  • Enduromi - The enduromi conquered the vandomar.
  • Synril - The synril claimed to have found the path to eternal peace, but were wiped out by the ditakur.
  • Vandomar - The vandomar were conquered by the enduromi.

Unidentified Milky Way Races

Many ancient races discovered across the galaxy are even less understood. While the ruins and artifacts they left behind may hint at their biology or technological advancement, in many cases the origins and even names of these races are not known. These unidentified races are listed here by the worlds their ruins were discovered on.

433 Spidau

Charted in 2185 by a deep-space mining vessel exploring the Nubian Expanse, the planet 433 Spidau was formerly inhabited by a sapient race, which destroyed itself through nuclear warfare around 1,000 years ago. Scans show the ruins of over ninety cities on the planet are still radioactive. Prior to this discovery, the contemporary galaxy knew of six other races that likewise perished in conflicts with nuclear weapons.

Alpha Centauri

In early 2186, a group of asari explorers discovered a primitive alien species on an unidentified planet in the Alpha Centauri system. While monitoring the species, the asari were ambushed by human colonists from the long lost Manswell Expedition of 2070.


Penetrating scans of the ice giant Anjea have revealed large numbers of hollow, unpowered objects, all with the same dimensions. "Sails" or "wings" appear to keep the objects aloft in Anjea's atmosphere. While the objects are too deep to be reached for study, a popular theory asserts that the objects are the "coffins" of an ancient race who laid their dead to rest in the gas giant.


Aphras was once inhabited by a sapient terrestrial avian race in its Bronze Age, before a series of massive impacts vaporized habitation centers and killed off most flora and fauna. The only trace of contemporary life on the planet is that of single-celled organisms in its seas. Of note, Aphras' sister-garden world, Tosal Nym, was also devastated by impacts similar to those on Aphras; however, it is not believed that Tosal Nym was inhabited by anything more complex than invertebrate sea life.


The remains of a primate-like spacefaring race have been found on the rock and ice world of Bothros. While the origins of this race are unknown, it has been confirmed that the race's habitation centers on Bothros were destroyed by orbital bombardments. Artifacts found on the planet range from melted metal fragments to the frozen remains of members of the race still wearing suits for extravehicular activity.


Carcosa was thought to be a naturally occurring hothouse planet until an asari expedition discovered palatial ruins on its barren surface. Likely the seat of an ancient city, the crumbling edifice dates back more than 2.7 million years. The only intact chamber appears to be a throne room, overlooking a large depression believed to have once been an enormous lake.

There is evidence that the people of Carcosa polluted their planet until it became uninhabitable, triggering a runaway greenhouse effect and spoiling the planet's fresh water supply.


An otherwise unremarkable semi-hospitable planet, Chasca possesses rings made of small pieces of synthetic material. The rings are nearly invisible from space, but from the ground they catch and scatter light in picturesque ways. It is unknown who made this example of "installation art", or why.


An automated helium-3 refueling station orbits the gas giant Cyllene. The Phi Clio system's remoteness from the nearest mass relay and the fuel station's archaic design imply that this system was once inhabited by a race who did not arrive through the relay but discovered it in independent FTL exploration. This same race may have built the geothermal and solar power stations found on the system's only other planet, Parnassus.


DC1938 was a small garden world that orbited the red supergiant SM2183 Rua and home to a spacefaring race that used crystalline structures in their technology. The planet was destroyed when its uranium core collapsed upon itself, a rare phenomenon called core fusion. More than five billion inhabitants are believed to have been killed by the catastrophe. The sole known survivor, an infant boy, was rescued by the human cruiser MSV Kent and taken to the Local Cluster for medical treatment.


Once a habitable garden world, Etamis is now completely barren, the oceans having dried up and the atmosphere lost. Regular crater patterns on the surface are evidence that Etamis was bombarded by dreadnought-class kinetic weapons. Relics found on Etamis show that an advanced spacefaring race lived there 20 to 40 million years ago. It is unclear if Etamis was the race's homeworld or a colony.


A standard hydrogen-helium gas giant, Farcrothu is only distinguished by its moons; several dozen of them have been sculpted into the likenesses of an arthropodal alien race not yet known to Council science. Radiometric dating suggests the moons were worked over half a million years ago.


Joab was originally inhabited by a spacefaring primate-like race. This race was wiped out thousands of years ago when all civilization centers were targeted in a massive orbital bombardment. Dust from the blasts blotted out light from the planet's star, killing all photosynthetic life and the fauna dependent on it. Contemporary scholars only know what they do about Joab's race through the discovery of time capsules buried by the race far from their cities.


Junthor was once a colony of an ancient spacefaring race. Ruins of this race's civilization, consisting of arcologies and other megastructures, still stand at a site near Junthor's equator. A pillar at the center of the ruins was covered in elaborate inscriptions which defied translation for centuries. When finally deciphered by asari linguists, the writing said only, "Walk among these works, and know our greatness." Crude scratches on the other side of the pillar said, "Monsters from the id."


The outermost of the gas giant Gamayun's six moons, Gigula, is the site of the well-preserved wreckage of an ancient alien starship. Thus far, the only information released to the public about the starship is that its internal layout suggests that the race that built it was horizontally-oriented.


Orbiting Mnemosyne was a Derelict Reaper. Cerberus estimates that 37 million years ago, this Reaper was disabled by a mass accelerator round fired by a weapon built by an unknown spacefaring race.


Ancient rock paintings on Namakli depict an anthropoidal race worshiping Leviathans.


The sunward hemisphere of the tidally-locked world of Siano bears the remnants of a complex of artificial structures in the north that are millennia old. Located on the opposite side are bunkers of radioactive waste ostensibly produced by primitive fission power plants. It is unclear if the structures were built on Siano before or after it entered the Dirada system millions of years ago.


The poorly preserved skeletal remains of an ancient humanoid race, along with primitive ceramic grave goods, were discovered at burial sites hidden in Vecchio's equatorial mountain ranges. Scholars question who once traveled to inhospitable Vecchio, since the nearest garden world, Volturno, has not given rise to intelligent life.

Identified Andromeda Races


One of the kett vassal races, the eelaen are a race that have been exalted past viable population. They now have become nomads who document and share knowledge.


One of the kett vassal races, the sirinde, which possibly translates as "eat their dead with reverence", have genetically poisoned themselves to stop exaltation, now have become dependent on kett neuroscience to survive.


One of the kett vassal races, the thusali once worshiped the Remnant

Unidentified Andromeda Races


H-019 is a cold, heavy-gravity world in the Heleus Cluster of the Andromeda galaxy. It was inhabited by a primitive intelligent species. Scans of their villages indicate that the Scourge drove them to extinction.


An enormous gouge on H-088's surface resembles an abandoned quarry and suggests a mining effort by ancient visitors.


A crater on Pas-40a contains an ancient metal object thought to be a torpedo from a space battle that took place centuries or millennia ago. It potentially predates Jardaan and angaran activity in the Heleus Cluster, which would mean it originated from a completely unknown species.


  • DC1938 is a reference to Superman. The planet's name references the publisher of the Superman comics (DC Comics) and the year in which the Superman comics debuted (1938). DC1938 is similar to Superman's homeworld, Krypton. Both orbited red stars (Krypton's primary was called Rao, while DC1938's is Rua) and were once inhabited by space-faring races that used crystalline structures in their technology. Each planet was destroyed when its radioactive core underwent a chain reaction, with only a single baby boy surviving and being taken in by humans. The name of the ship that rescued the sole survivor of DC1938 (the MSV Kent) is a reference to Superman's adopted Earth surname (Kent).