Lex Luthor is one of Superman's most popular enemies even though he's only human he is one of Superman's most dangerous enemies in Super Friends he is the leader of the legion of doom a group of villains bent on destroying the Super Friends in Superman the Animated series he is a powerful business man who is secretly involved with several crimes in Justice League and it's successor Justice League Unlimited Luthor gets kryptonite cancer and merges himself with Brainiac to destroy the Justice League later he takes over the Secret Society from Grodd and ends up saving the universe from Darkseid