Apollo Creed
Apollo Creed is the antagonist in Rocky I and Rocky II, after which he befriends Rocky and is his main ally through the beginning of Rocky IV.
He is very evenly matched with Rocky and their fights are close-run contests. They fight an additional match off-camera at the end of Rocky III, the outcome of which is unknown.
Apollo is presumably named for the Greek god Apollo, who was kind of showy and presented things in a good light.