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.