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Floyd Patterson

1956-59; 1960-61

Patterson, who at the time was the youngest fighter to win the lineal heavyweight championship (at age 21), shared the ring with the best of his generation, including Muhammad Ali, Sonny Liston, Archie Moore and Ingemar Johansson.

Patterson won the vacant title (after Rocky Marciano abdicated it to retire) against Moore in 1956 and became the first heavyweight to regain the undisputed championship. Patterson lost the title to Johansson in 1959 but regained the belt against the Swedish fighter a year later. In 1962, Patterson was knocked out by Sonny Liston in the first round, but he would go on to fight for another decade and finish with a record of 55-8-1 (40 KOs).