Boxer Marvelous Marvin Hagler born in Newark, New jersey on this date. Marvelous Marvin Hagler was the undisputed middleweight champion of the world from 1980 – 1987. Hagler made twelve undisputed title defenses and holds the highest KO percentage of all middleweight champions at 78 percent.  In 1982, annoyed that network announcers often did not refer to him by his nickname, “Marvelous”, Hagler legally changed his name to Marvelous Marvin Hagler.