Muhammad Ali boxed.
Muhammad Ali ( [ ɑːˈliː ] born Cassius Marcellus Clay Jr. ; January 17 , 1942 -- June 3 , 2016 ) was an American professional boxer and activist . Clay then converted to Islam and changed his name from Cassius Clay , which he called his `` slave name '' , to Muhammad Ali . The World Boxing Association ( WBA ) is the oldest and one of four major organizations which sanction world championship boxing bouts , alongside the IBF , WBC and WBO .