Cassius Clay, who later renamed himself Muhammad Ali, trains with a punching bag for the 1960 Olympic Games.
Shoes for a champ
Proudly wearing his gold medal, Clay buys a new pair of shoes at a shop in Rome, Italy, on Sept. 6, 1960. Clay won the gold medal by defeating Poland's Ziggy Pietrzykowski in the light-heavyweight championship bout.
Clay, sporting a train porter's cap, jokes around while showing his name on a fight card to porter Herbert Sims on March 6, 1963. Clay was always known for his big punch and bigger mouth.
Pairing of personalities
Howard Cosell, one of the most famous sports broadcasters of all time, interviews Ali after his victory over Bob Foster at South Lake Tahoe, Nev., on Nov. 21, 1972.
Praying to Allah
Ali kneels in prayer during his visit to the Islamic Center in Tokyo on March 24, 1972, before a workout at a local gym. Ali was training for his April 1 bout against Mac Foster, which Ali won. Ali shocked the world when he announced on Feb. 28, 1964, that he was joining the Nation of Islam, one of the most controversial organizations in the United States.
Take that, Sonny!
Ali stands over Sonny Liston after knocking him down during the first round of their bout on May 25, 1965, in Lewiston, Maine. Ali defeated Liston for the second time to retain his title as heavyweight champion.
Time to rumble
In a fight known as the "Rumble in the Jungle" Ali knocks down George Foreman on Oct. 29, 1974, in Kinshasa, Zaire. Ali won in the eighth round to regain the heavyweight championship. He used his "rope-a-dope" strategy, in which he let Foreman pin him against the ropes and swing away, tiring himself out. Then Ali attacked.
Muhammad Ali and Malcolm X attend a function on Jan. 1, 1964, in Miami. Weeks later, Ali would announce he was joining the Nation of Islam, of which Malcolm X was a member.
Ali throws a punch at Joe Frazier during their bout at Madison Square Garden in New York on Jan. 28, 1974. Ali won in 12 rounds, avenging his 1971 loss.
KO'd in court
Surrounded by newsmen and admirers, Ali looks skyward as he leaves federal court in Houston on April 27, 1967, after a federal judge tossed out his last legal effort to avoid being drafted into the U.S. Army. But Ali refused to report for induction on April 28 and was later prosecuted by the Justice Department.
Losing to Leon
In one of the biggest upsets in boxing history, Ali loses to challenger Leon Spinks in 15 rounds on Feb. 15, 1978. Here, Ali grimaces as he sustains a stinging right cross in the third round.
Hell, no, we won't go
Ali accepts flowers from one of an estimated 12,500 people who marched to San Francisco City Hall to end a week-long draft protest on April 27, 1968.
Honor for 'The Greatest'
Ali lights the Olympic flame on July 19, 1996, as Olympic champion swimmer Janet Evans looks on to kick off the Summer Olympics in Atlanta.
Ali kisses the gold medal he received from Juan Antonio Samaranch, president of the International Olympic Committee, during the men's basketball championship game at the Sydney Summer Olympics on Aug. 3, 2000. Ali is said to have thrown away his original medal in protest against the Vietnam War in the early 1960s.
Like father, like daughter
Ali congratulates his daughter Laila Ali on June 11, 2005, after her third-round TKO of Erin Toughill for the WBC/WIBA super middleweight championship.
The highest honor
President Bush presents the Presidential Medal of Freedom, the nation's highest civil award, to Ali in the East Room of the White House on Nov. 9, 2006. The medal is presented to those who have made contributions to national security, world peace or culture. It was Ali's first public appearance in five months.