Lex Luthor (Silver Age)
The young Lex Luthor was a friend of Superboy, and he would often visit Luthor's lab. During one such visit, a lab accident took place which caused all of Luthor's hair to fall out permanently. Unable to accept that it was just an accident, Luthor believed that Superboy caused the accident out of jealousy, and vowed to take revenge. From then on, one of the most brilliant minds of Earth was devoted only to creating fantastic new weapons to use against Superman and conquer the galaxy.