Rocky Marciano was the only undefeated boxing champion in any weight division (until Joe Calzaghe retired 46-0 in 2009). At the end of his career he was 49-0, with 43 of his victories coming by knockouts. Rocky made his boxing debut in 1947 at the age of 24 in Holyoke, Massachusetts, by knocking out Lee Epperson in the third round. He went on to fight such legends as Joe Louis and Jersey Joe Walcott. On September 23, 1952, in Philadelphia, Marciano KO'd Walcott in the 13th round to win the Heavyweight Championship of the World. He fought his last boxing match on September 21, 1955, knocking out "The Mongoose" Archie Moore in the ninth round at Yankee Stadium. He announced his retirement on April 27, 1956. On August 31st, 1969--the eve of his 46th birthday - Marciano was killed in an airplane crash. Although he's been gone more than 30 years, he's still revered today as one of the greatest fighters in the sport.