Rocky Marciano, an American boxer of Italian descent, defended his National Boxing Association heavyweight title against English boxer Don Cockell on 16 May 1955, at Kezar Stadium in San Francisco. Marciano defeated his challenger with a technical KO in the ninth round.

In his 49 fights (49 wins), Marciano had 43 knockouts, for a knockout-to-win ratio of 87.76%, the highest of all heavyweight world champions in the history of professional boxing. Marciano ended his career as the first undefeated heavyweight world champion and is considered one of the most successful boxers in the history of the sport, by virtue of this accomplishment as well as his high knockout-to-win ratio. He was world champion from 1952 to 1956. Marciano died in an airplane crash on the day before his 46th birthday.

Rocky Marciano was inducted into the International Boxing Hall of Fame in 1990.

The challenger, Don Cockell, was the British heavyweight champion.