Rocky was inspired partly by Muhammad Ali's 1975 fight against which boxer?

Rocky was partly inspired by Muhammad Ali’s 1975 fight against Chuck Wepner.

Wepner challenged Ali for the world heavyweight championship at Richfield Coliseum in Ohio on March 24, 1975. Although Ali ultimately won by technical knockout in the 15th round, Wepner lasted far longer than many expected and briefly knocked Ali down. The underdog’s determination strongly affected Sylvester Stallone.

Stallone watched the bout and soon began writing the screenplay for Rocky. The film’s central idea—a largely unknown fighter receiving an unlikely title opportunity and proving he belongs—echoes Wepner’s experience, though Rocky Balboa is a fictional character rather than a direct biography.

The inspiration was broader than one fight. Stallone also drew on fighters including Rocky Marciano and Joe Frazier, while Apollo Creed contains clear elements associated with Ali. Wepner later sued Stallone over the connection; the case was settled out of court.