List of world heavyweight boxing champions

At boxing's beginning, the heavyweight division had no weight limit, and historically the weight class has gone with vague or no definition. During the 19th century many heavyweights were 170 pounds (12 st 2 lb, 77 kg) or less, though others weighed considerably more. John L. Sullivan was the first widely recognized champion under Marquess of Queensberry rules. Known as the "Boston Strong Boy," Sullivan weighed around 200 pounds when in shape, and helped transition the sport from its bare-knuckle era. Sullivan would be defeated for the title by "Gentleman" Jim Corbett over 21 rounds on September 7, 1892, the first heavyweight titleholder solely under Queensberry rules.

In 1920, a de facto minimum weight for a heavyweight was set at 175 pounds (12 st 7 lb, 79 kg) with the standardization of a weight limit for the light heavyweight division. The addition of the cruiserweight division, which began in 1979, reset the de facto minimum, first to 190 pounds and then to 200 pounds in 2004 when boxing's major sanctioning bodies universally raised the weight limit at which they'd recognize champions. The World Boxing Council created a new division called bridgerweight for boxers weighing between 200 and 225 pounds. As of June 2022, no other major organization has recognized the division.

The championship of the heavyweight division has been fractured or disputed at various times in its history. Until the 1960s, such disputes were settled in the ring, typically with alternate title claimants largely being forgotten. The rise of sanctioning organizations, however, have produced an environment where typically there is no single world heavyweight champion, with titleholders recognized by one of these organizations (a "World Champion") or more (a "Super Champion," a "Unified Champion," or, in the rare cases where the four most prominent organizations recognize the same boxer, an "Undisputed Champion").

Some title reigns are considered dubious owing to long periods of inactivity, the legitimacy of the organization granting championship recognition, and other factors. In 1967, for example, Muhammad Ali was denied a boxing license in every U.S. jurisdiction and stripped of his passport because of his refusal to be inducted into the armed forces. On April 29, 1967, his recognition as champion by both the World Boxing Association and World Boxing Council was withdrawn. Yet Ali remained the lineal champion and was recognized by The Ring magazine and most boxing purists until his defeat in 1971. In pursuit of greater revenues, some organizations have now adopted a practice of simultaneously recognizing multiple champions in a weight division, creating a situation in which a champion may be unable not only to secure recognition from multiple sanctioning bodies but to secure sole recognition from a single one.