List of world heavyweight boxing champions

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.

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.

The Ring has recognized heavyweight champions during two periods, commencing with its inaugural issue in 1922 and continuing until the 1990s, then again from 2002 to the present day.

A third entity, the European Boxing Union (IBU) would follow suit, but with limited exception in the heavyweight division the three organizations recognized the same champion.

At its 1962 convention, the NBA's non-United States members exploited a membership rule and took effective control of the organization, rebranding it as the World Boxing Association.