In Rocky III, what is the name of Rocky Balboa's opponent who becomes his ally?

In Rocky III, Rocky Balboa's former opponent who becomes his ally is Apollo Creed.

Apollo begins the series as Rocky's opponent, but their relationship changes after Rocky loses the heavyweight title to Clubber Lang. Apollo offers to help Rocky regain his speed, timing, and confidence, training him at a gym in Los Angeles.

Their partnership is one of the major turning points in the franchise. Apollo understands Clubber's aggressive style and teaches Rocky techniques that contrast with Mickey Goldmill's earlier approach. The training culminates in Rocky's rematch with Lang.

Apollo's role as Rocky's mentor continues in Rocky IV, when the two remain close friends. Apollo's death during an exhibition match with Ivan Drago then motivates Rocky's international challenge against the Soviet boxer.