Born Cassius Marcellus Clay in 1942 in Louisville, Kentucky, Muhammad Ali (he changed his name after joining the Nation of Islam in 1964) is a three-time world heavyweight champ, a gold medal Olympian, a sport and culture icon, and one of the greatest and most charismatic athletes America has ever produced.

In 1967, while heavyweight champion of the world, Ali refused to be inducted into the U.S. military, citing his religious beliefs and is public opposition to the War in Vietnam. He was stripped of his boxing title, and did not fight again for nearly four years.

A master strategist in the ring as well as, when necessary, a devastating puncher, Ali was involved in some of boxing's greatest matches, including three against his lifetime rival Joe Frazier, and one with George Foreman ("The Rumble in the Jungle") in 1974 that was chronicled in the great documentary film, "When We Were Kings."

In his later years, Ali developed Parkinson's disease due to injuries he sustained through his long (some say too long) career. In 1999, Sports Illustrated named him "Sportsman of the Century," while the BBC once crowned him "Sports Personality of the Century."