Rocky Marciano was an American professional boxer who competed from 1947 to 1955. He is best known for being the only heavyweight champion in boxing history to retire undefeated, with a record of 49 wins and 0 losses. Marciano was known for his powerful punches and relentless fighting style, which earned him the nickname "The Brockton Blockbuster." Born on September 1, 1923, in Brockton, Massachusetts, Marciano's boxing career began after serving in World War II. He became the heavyweight champion in 1952 and successfully defended his title six times before retiring in 1956. His legacy continues to influence the sport of boxing today.