Computron (Earth-68)

For Canon info, see

John Smith 10
Computron is a minor villain, though his robot minions have appeared more often than him.

He first appeared in Hero Time (John Smith 10), where he was freed from Dimension 12, and was defeated by Captain Nemesis and John.

He returns in Galactic Battle with his minions to fight John, Gwen and Kevin. After an explosion teleports John halfway across the galaxy, it became uncertain what happened, though it can be assumed that Gwen and Kevin won. It's unknown whether he survived or not.