Rocky Marciano was Italian-American and was born Rocco Marchegiano (pronounced 'mark-uh-jahno').
He was the only HW champ to retire with a perfect record - he was 49-0 as a pro but he lost a few of his 12 amateur fights.
His closest pro fights were a split decision win vs Roland LaStarza and a 13 round ko vs Jersey Joe Walcott.
He scraped through vs LaStarza but won a rematch a few years later in 1953 - knocking LaStarza out and causing severe damage to LaStarza's arms, where LaStarza had been blocking Rocky's punches.
Rocky was trailing on all three judges scorecards in the first Walcott fight, before a short right to the jaw nearly took Walcott's head off.
Marciano stood only 5 feet 10 and a half inches (70.5 inches) tall. His reach (outstretched arms, fingertip to fingertip) was a mere 67.5 inches - shorter than many lightweights'. For comparison, here are the reaches of Mike Tyson (71') ... Joe Frazier (73') ... Muhammad Ali (79') ... and Sonny Liston (84').
Mariano weighed 184 lbs for the first Walcott fight. For his last fight, vs Archie Moore, Rocky weighed 189 lbs.
Rocky's weight was remarkable for two reasons.
First, he was extremely light for a heavyweight - if he were fighting today, he'd be classed as a cruiserweight, not heavyweight.
Second, Rocky's weight was 190 lbs and more when he fought as an amateur - his professional fighting weight was actually lighter than that (he was always under 190 lbs for his pro fights). This trend is opposite to most other HW fighters. Rocky felt he had the strength and punching power but always wanted to be light, as fast as possible, and highly conditioned with lots of stamina.
Rocky's training camps were sometimes five or six months long. (Most fighters' training camps last about eight weeks.)