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. An effort is currently underway to establish an additional  division at approximately 225 pounds, with the International Boxing Organization and World Boxing Council each announcing they would recognize champions in this new "super cruiserweight" class. 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, has produced an environment where typically there is no single "Heavyweight Champion of the World," 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 On April 29, 1967, his recognition as champion by both the World Boxing Association and World Boxing Council was withdrawn.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 defeated in 1970. 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. Championship recognition. Public Acclamation: 1884 to 1921. Champions were recognized by wide public acclamation. A heavyweight champion was a boxer who had a notable win over another notable boxer and then went without defeat. Retirements from the  ring periodically led to a "true" champion going unrecognized, or for several to be recognized by the public for periods of time. Typically, public interest in having a single, "true" champion resulted in claimants to the heavyweight title being matched with one another; the winner of that bout was subsequently deemed the champion, with the claim (and title lineage) of the defeated boxer largely forgotten. Sanctioning Bodies: 1921 to present. The National Boxing Association (NBA), was formed in 1921 as the first organization aimed at regulating boxing on a national (and later global) level. The prominence of New York City  as the epicenter of boxing would lead to a governmental entity, the powerful New York State Athletic Commission (NYSAC), to join the NBA in sanctioning bouts as "world championships." A third entity, with lesser public recognition, the European Boxing Union (EBU), would follow suit, with this triumvirate typically (but not always) recognizing the same boxers as world champions. At its 1962 convention the NBA's non-U.S. members exploited a membership rule and took control of the organization, rebranding it the World Boxing Association. The (WBA), was joined a year later by a combination of state and national boxing commissions  (including the NYSAC and IBU) to form a separate sanctioning body, the World Boxing Council (WBC). Each organization would later have a spin-off competing sanctioning body emerge: the International Boxing Federation (IBF), which was formed by members of the United States Boxing Association in 1983; and the World Boxing Organization (WBO), which was formed in 1989. A fifth significant (but not as publicly accepted) body came in the form of the International Boxing Organization (IBO), in 1991, and today there are over a dozen sanctioning organizations, of varying degrees of public acceptance, sanctioning bouts as for a world championship  and proclaiming their heavyweight winners "Heavyweight Champion of the World." The Ring: 1922 to present. From its outset until the 1990s, and again since 2002, "The Ring" has recognized heavyweight champions. Under its original policy a champion won the title either by defeating a recognized champion or winning a bout between the magazine's top-rated contenders. Once recognized as champion, championship recognition could be lost only by death, retirement, or loss. In 2012 these policies were revised so that a champion could be more readily recognized, and expanding the means by which championship recognition could be withdrawn (specifically, by  not scheduling a fight with a top five rated contender for two years, or any bout at all for 18 months). Current status of prominent championship titles. World Boxing Association The World Boxing Association presently recognizes up to four distinct 'types' of champion in its weight divisions: a 'Super' Champion (one who holds the WBA title along with that of at least one other widely recognized sanctioning body), a 'Regular' Champion (one who holds the WBA title alone), a 'Champion in Recess' (a champion who retains some form of championship recognition, but for reasons beyond their own control are presently  inactive), and a 'Gold' Champion (a designation which the organization's governing documents don't explain). The organization also recognized a fifth type of champion, an 'Interim' championship who, ostensibly, held the title during a period of illness or injury to a 'Super' or 'Regular' titleholder. The organization vacated interim titles at every weight division on August 25, 2021. The current status of these titles is as follows: World Boxing Council The World Boxing Council presently recognizes up to five distinct 'types' of champion in its weight divisions: a 'Franchise' Champion (one who holds the WBC title along with that  of at least one other widely recognized sanctioning body; a distinction it has thus far only awarded once), a 'World' Champion (ostensibly one who holds the WBC title alone, but to date no unified champions in the heavyweight division have been attributed the 'Franchise' Champion status), an 'Interim' Champion (one who, ostensibly, holds the title during a period of illness or injury to the 'World' Champion), a 'Champion in Recess (a champion who retains some form of championship recognition, but who are presently inactive), and a 'Silver' Champion (a designation which has no clear distinction, but which nevertheless is recognized  as a world championship-level title). The current status of these titles is as follows: International Boxing Federation The International Boxing Federation recognizes but a single champion in the heavyweight division. World Boxing Organization The World Boxing Organization recognizes up to three distinct 'types' of champion in its weight divisions: a 'Super' Champion (one who holds the WBO title along with that of at least one other widely recognized sanctioning body), a 'World' Champion (though unlike the WBA, if a WBO 'Super' Champion exists a separate 'World' Champion is not simultaneously recognized), and an 'Interim' Champion (one who holds the  title during a period of illness or injury to the 'Super' or 'World' Champion). At present, however, there is a single titleholder: The Ring List of combined reigns. "As of September 25, 2021". Keys: List of individual reigns. The list includes "The Ring" belt. Career total time as champion (for multiple time champions) does not apply. Keys: