Muhammad Ali 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.He is one of the most recognized sports figures of the past 100 years, crowned "Sportsman of the Century" by Sports Illustrated and "Sports Personality of the Century" by the BBC.

Ali, originally known as Cassius Clay, began training at 12 years old and at the age of 22 won the world heavyweight championship in 1964 from Sonny Liston in a stunning upset. Shortly after that bout, Ali joined the Nation of Islam and changed his name. He converted to Sunni Islam in 1975, and 30 years later began adhering to Sufism.