- 7 U.E.M
- 5 UbH-IceIst
- 3 UBX Master
- 2 UEd2
- 12 UEM
- 2 UFO
- 3 uG-x`[ToM]
- 2 UK-Scorpion
- 2 Ulo & Einheit
- 3 UltraSonic
- 4 Ulysses_30
- 2 Un1ucky
- 2 Uncle Bob
- 27 Uncle_Bob
- 20 Uncledumpy
- 9 Uncommon
- 2 UnconnecteD
- 5 Underscore
- 6 Undertaker
- 2 UndrSiege
- 10 UnFuKWitAbLE
- 2 UnholyCreator
- 7 Union
- 2 United Scriptors
- 2 United Scriptors : »SZO«Zeß
- 2 United Scriptors: {NYA}Thainnin
- 3 United Scrptors
- 2 UnitedSniperMappers
- 2 Unknown (original), EvilGrins (edited)
- 2 UNKNOWN! REMIXED BY {DMF}SAVAGE
- 2 Unknown, CTFM Conversion"Karlos"
- 4 Unknown, editedEric "DarMonkey" Olson
- 5 Unknown/FixesBarbie
- 2 Unknown/ModdedBarbie
- 7 UnLeaded
- 2 Unofficial
- 7 UnPfhorgiven
- 6 UnrealGGecko
- 2 unrealKillers.com
- 6 UNREALLOCO
- 2 Unseen[WOLFIN]
- 7 UnShame
- 4 unXceptable
- 7 UN||XpanD
- 2 Upaul
- 2 ur^Worlock
- 4 Uri19
- 3 urPackage
- 8 usaar33
- 4 Usama
- 2 usolsons
- 2 UT2003>UT ConversionHoward_Stern
- 2 UT2k4:Nagashi - UT99:Ghandi
- 3 UTCP Maddmapper: Dave {Maddog} Mortensen
- 7 utdemon
- 2 UTGhost / Ryu_Senshi
- 2 utinstafreak
- 4 UTPG and OldUnreal
- 2 Uwe "Rockhound" Goetz
- 2 Uwe 'Fierce' Herrmann