What is the name of the heavyweight champion in Rocky Balboa?

The heavyweight champion in Rocky Balboa is Mason Dixon. Nicknamed “The Line,” Dixon is the reigning undisputed world heavyweight champion when the film begins, though his unpopular reign is questioned because he has not faced a truly formidable opponent.

Dixon is played by real-life professional boxer Antonio Tarver, who had won multiple light-heavyweight world titles before appearing in the film. The story sets up a contrast between Dixon's modern, commercially managed career and Rocky Balboa's legacy as an older former champion who has long since retired.

An ESPN computer simulation showing Dixon losing to Rocky sparks public interest in a charity exhibition match in Las Vegas. Although many expect Rocky to be overwhelmed, the bout lasts ten rounds. Dixon wins by a narrow split decision, preserving his undefeated record while Rocky earns renewed respect. Pretty Ricky Conlan, Union Cane, and Tommy Gunn are also boxers in the franchise, but none is the champion identified in this film.