Muhammad Ali (born Cassius Marcellus Clay Jr., January 17, 1942 in Louisville, Kentucky, U.S.) is a retired American boxer and three-time World Heavyweight Champion, who is widely considered to be one of the best heavyweight boxing champions ever. As an amateur, he won a gold medal in the light heavyweight division at the 1960 Summer Olympics in Rome. As a professional, he became the first person to win the lineal heavyweight championship three times.

In 1999, Ali was crowned "Sportsman of the Century" by Sports Illustrated and "Sports Personality of the Century" by the BBC.

Ali changed his name from Cassius Clay to Muhammad Ali after joining the Nation of Islam in 1964, subsequently converting to orthodox Islam in 1975. In 1967, Ali refused to be inducted into the U.S. military based on his religious beliefs and opposition to the war in Vietnam. He was arrested and found guilty on draft evasion charges, stripped of his boxing title, and his boxing license was suspended. He was not imprisoned but did not fight again for nearly four years while his appeal worked its way up to the U.S. Supreme Court.