Marvelous Marvin Hagler (born Marvin Nathaniel Hagler; May 23, 1954)[1] is an American former professional boxer who competed from 1973 to 1987. He reigned as the undisputed middleweight champion from 1980 to 1987,[2] making twelve defenses of that title, and currently holds the highest knockout percentage of all undisputed middleweight champions, at 78%, while also holding the second longest unified championship reign in boxing history at twelve consecutive defenses.