| Abbreviation | Definition |
|---|---|
| UED | United Earthen Dominion |
| UEL | United Earth League |
| UEL | United Empire Loyalist |
| UESPA | United Earth Space Probe Agency |
| UFB | United Fans of Buffy |
| UFC | United Federation Catalog |
| UFO | Unidentified Flying Object |
| UFO | United Future Organization |
| UFO | Unknown From Outerspace |
| UFP | United Federation Of Planets |
| UG | The United Galaxy |
| UGC | United Galactic Commonwealth |
| UGM | UnderGround Master |
| UGP | Ultimate Galactic Pandemonium |
| UIM | Ubitron Interface Module |
| UIP | United Interstellar Planets |
| UJA | United Jedi Alliance |
| UKG | U K Garrison |
| ULTIMATUM | Underground Liberated Totally Integrated Mobile Army To Unite Mankind |
| ULZ | Urban Legend Zeitgeist |