List of fictional alien species: U
| Name | Source | Type |
|---|---|---|
| Ul-Mor | Star Frontiers | nomadic land octopi |
| Umgah | Star Control | |
| Unas | Stargate SG-1 | |
| Uncreated | Marvel Comics | |
| Unggoy | Halo | |
| Ungooma | Ascendancy | |
| Uniocs | Schlock Mercenary | |
| Unity | Superman: The Animated Series | |
| Ur-Quan Kzer-Za | Star Control | |
| Ur-Quan Kohr-Ah | Star Control | |
| Utrom | Teenage Mutant Ninja Turtles | |
| Uryuoms | El Goonish Shive | |
| U'tani | Star Trek | |
| Utwig | Star Control | Humanoid |