Rocky Marciano was born September 1, 1923.
While his first name is better-known in popular culture as the namesake of the "Rocky" boxing franchise, Marciano was a star long before Sylvester Stallone adopted the name.
Known for incredible stamina and a broad, sturdy chin, Marciano set standards that haven't been matched even today. He remains the only person to win a heavyweight title and never lose or tie a match. He held the title for nearly four years, defended the belt successfully on six separate occasions.
He retired from boxing with a perfect 49-0 record, winning 43 by knockout. His 87.75 knockout percentage is also the best in professional boxing history.
Muhammad Ali held Marciano in such high regard that he isn't sure he could have beaten the boxer in his prime:
Marciano and Ali had a friendly relationship in the 1960s, with Marciano once insisting that he could beat Ali even a decade after his retirement. Unfortunately, Marciano's life was cut short: In August 1969, one day before his 46th birthday, a small plane carrying Marciano crashed amid bad weather.
In the wake of his tragic loss, Marciano is remembered as one of the greatest boxers in history.