Jungle Jim
Jungle Kitty
Juninho
Junior
Junior Mint
Junior Partner
Juniper
Junkyard
Junkyard Dog
Juno
Jup Jup (after the character in the children's show "Hi-5")
Jupiter
Jurgen
Jury Duty
Just
Just a Minute
Just in Time
Just Jack (after the character on the Will & Grace tv show)
Justa
Justa Boy
Justa Girl
Justa Kitty
Justice
Justin
Justin Tyme
Justine
Justus
Justy
Jutta
Jynx
Jynxetta
Jynxetta Puny-pants (sweety-kitty) Pendragon
Jyrky
Jzero