Ultraviolet
Ulysses
Uma
Uma (after the actress Uma Thurman)
Umbra
Umgow (after the old Tarzan movie word which meant anything)
Umgowa
Umi
Umka
Umma (Turkish for "hope")
Umpa Lumpa
Unagi
Unbee
Unbelievable
Uncle
Uncle Buster
Uncle Charles
Uncle Charles Willoughby
Uncle Charlie
Uncle Eeker
Uncle Fester
Uncle Marshmallows
Uncle Pee
Unco
Uncommon
Under My Foot
Under My Thumb
Underdog
Underfoot
Undun