Who is the youngest undisputed heavyweight boxing champion of all times?

Floyd Patterson (January 4, 1935 – May 11, 2006), an American professional boxer, held the undisputed world heavyweight championship. At the age of 21, he became the youngest boxer to win the world heavyweight title, and was also the first heavyweight to regain the title after losing it. In professional boxing, to be the "undisputed" champion of a weight class, the boxer has to be recognized as the world champion in the class group by each and every boxing organization. At the time, Patterson was acknowledged by the authorities of all the official boxing organizations as the undisputed heavyweight champion. No organization questioned Patterson's right to the championship.

Although Mike Tyson later became the youngest boxer to win a world heavyweight title at the age of 20, Floyd Patterson remained and is the youngest undisputed heavyweight champion of all time. No younger fighter has a claim over Patterson. With Tyson, some boxing organizations could not agree on his right to the title.

It was on November 30, 1956, for the World Heavyweight Championship that Patterson beat Archie Moore by a knockout in five rounds to become the youngest World Heavyweight Champion in history, at the age of 21 years, 10 months, 3 weeks and 5 days.

He was also the first Olympic gold medalist to win a professional Heavyweight Boxing Championship title. As an amateur he represented the United States at the 1952 Olympics, winning a gold medal in the middleweight division.