Muhammad Ali (/ɑːˈliː/; born Cassius Marcellus Clay, Jr.; January 17, 1942) is an American former professional boxer, generally considered among the greatest heavyweights in the history of the sport. A controversial and polarizing figure during his early career, Ali is now highly regarded for the skills he displayed in the ring plus the values he exemplified outside of it: religious freedom, racial justice and the triumph of principle over expedience.