- Iron Knight
- Ironhammer the Giant
- Jack's Knight
- Jawsman
- Jellyfish
- Jerry Beans Man
- Jester Confit
- Jester Lord
- Jester Queen
- Jet Gauntlet
- Jetroid
- Jigen Bakudan
- Jinzo
- Jirai Gumo
- Joe the Pixie
- Jowgen the Spiritualist
- Judge Man
- Jumbo Drill
- Junk Archer
- Junk Berserker
- Junk Collector
- Junk Destroyer
- Junk Robot Camelcycle
- Junk Robot Cleanaga