Lex Luther
Lex Luther is arch enemy with Superman. He has a lab filled with Kryptonite, which is Superman's weakness. His base is the Hall of Dome.
The Joker
The Joker arch enemy to Batman. Joker likes to hang out with Lex Luther. His base is the Joker's Playhouse.
Gorilla Grodd
Gorilla Grodd is a giant monster monkey. He also is friends with Joker. He likes to fight Batman.