Muhammad Ali (born Cassius Marcellus Clay Jr. on January 17, 1942) is a retired American boxer and former three-time World Heavyweight Champion and winner of an Olympic Light-heavyweight gold medal. In 1999, Ali was crowned "Sportsman of the Century" by Sports Illustrated and the BBC.
Ali was born in Louisville, Kentucky. He was named after his father, Cassius Marcellus Clay Sr., who was named for the 19th century abolitionist and politician Cassius Clay. Ali changed his name after joining the Nation of Islam in 1964 and subsequently converted to Sunni Islam in 1975.