| Description | Race | Homeworld |
| Naturally war-faring species that were uplifted by the Council to help fight in a major galaxy-wde conflict | |
| Doomsday-bearing race that are composed of a mix of organic and synthetic parts; responsible for the mass extinction events every 50,000 years | |
| Race most associated with piracy and underworld affairs by most species; partly responsible for the Skyllian Blitz | |
| Mysterious re-purposed race that abducted several major human colonies across the Terminus Systems | |
| Amphibian race that were uplifted and taken from their arid homeworld and transported to one of another Council race and trained as assassins | |
| Violent race that are extremely adaptable (in terms of their physiology) to any environment; main components of the 'Blood Pack' mercenary group | |
| Ancient space-faring civilisation that were wiped out in a mass-extinction event 50,000 years prior to ME: 1; most species of the galaxy thank them for the mass relays and Citadel | |
| Sentient insect race thought to have been extinct from the galaxy for centuries prior to the events of ME: 1; can inhabit the bodies of other in order to communicate | |
| Sentient humanoid race known for natural aggression and possess a pack mentality in their culture | |