10James J. Corbett – Championship Reign: 4 Years, 6 Months, 10 Days
We begin with a man some call the ‘father of boxing’. Corbett, an American, competed in the late 19th century and the early 20th century, a time when boxing was still known as ‘prizefighting’. His use of bobbing, weaving, and other standard boxing movements of the modern game was
innovative at the time. His artistic approach to the sport was a precursor to what we watch today, and it allowed him to build a large following. He won the Heavyweight Championship from John L. Sullivan in 1892, using feints and jabs to wear him down until knocking him out in the 21st round. Boxing was illegal in many states at the time, and no athletic commissions existed, so organizing championship defenses was a tedious affair. He defended the belt only once during his 4 ½ year reign, before eventually losing the championship to Bob Fitzsimmons.