Born Cassius Marcellus Clay, Jr., on Jan. 17, in Louisville, Ky., to Odessa and Cassius, Sr. (a sign and mural painter).
After having his bike stolen, a 12-year-old Clay promises to "whup whoever stole it." In an attempt to channel his aggression, the policeman he reported the crime to takes him under his wing and eventually directs him to boxing trainer Fred Stoner. Over the next six years, Clay would win six Kentucky Golden Gloves championships, two national Golden Gloves titles, and two AAU (Amateur Athletic Union) crowns.
Clay wins the light-heavyweight gold medal at the Summer Olympics in Rome with a 5–0 decision over Poland's Zbigniew Pietrzykowski.
Upon returning to his native Louisville, Clay finds he's not immune to the racism that is so prevalent in the U.S. After being refused service by a waitress at a "whites-only" restaurant, and then fighting with a white gang, a disgusted Clay throws his gold medal into the Ohio River.
He turns professional and wins the first two fights of his career.
Despite an unblemished 19–0 record, Clay is a heavy underdog in his championship bout with Sonny Liston. But you wouldn't know it by listening to him. He brashly and colorfully predicts victory, and teases the champ by calling him, among other things, an "ugly, old bear."
True to his word, Clay has his way with Liston through six rounds. When Liston refuses to leave his corner for the start of the seventh, the fight ends and Clay becomes heavyweight champion of the world.
After the fight, Clay announces he has become a Black Muslim and has changed his name to Muhammad Ali.
In April, Ali refuses induction into the U.S. Army due to his religious convictions. He angers many Americans after claiming, "I ain't got no quarrel with those Vietcong." He is subsequently stripped of his WBA title and his license to fight.
In June, a court finds him guilty of draft evasion, fines him $10,000, and sentences him to five years in prison. He remains free, pending numerous appeals, but is still barred from fighting.
Due to a loophole (there was no state boxing commission in Georgia), Ali returns to the ring in Atlanta and knocks out Jerry Quarry in three rounds.
In March, he fights heavyweight champ Joe Frazier in Madison Square Garden. A left hook by Frazier knocks Ali down in the 15th round. Frazier wins by unanimous decision.
Three months later, the Supreme Court rules in his favor, reversing the 1967 draft-evasion conviction.
In January, he gains a measure of revenge from Frazier, besting the former champ in 12 rounds.
Regains the heavyweight title in the "Rumble in the Jungle" on Oct. 30 in Kinshasa, Zaire after knocking out champion George Foreman in the eighth round. He successfully uses his "rope-a-dope" strategy—Ali allowed Foreman to get him against the ropes and swing away until he tired himself out. Then Ali attacked.
Ali fights Frazier for the third time at the "Thrilla in Manila" in the Philippines. The two heavyweights batter and bloody each other in a ferocious battle, but Ali retains his belt when Frazier can't come out for the 15th round.
With a career record of 55–2, an overconfident Ali loses his belt to 1976 Olympic champ Leon Spinks in a 15-round split decision. Spinks' reign as champ is brief, however, as Ali wins back the title in a unanimous decision seven months later.
Announces his retirement on June 27.
Comes out of retirement to fight new heavyweight champ Larry Holmes. Holmes punishes Ali, landing an estimated 125 punches in the ninth and tenth rounds alone, and then knocks him out in the 11th.
Loses a unanimous decision to Trevor Berbick, and finally hangs up the gloves for good, retiring with an overall professional record of 56—5.
Ali is diagnosed with Parkinson's disease, a neurological disorder whose symptoms include muscle tremors and slowness of speech.
Ali carries the Olympic torch and ignites the cauldron to signal the beginning of the Summer Olympics in Atlanta. He is also given a second gold medal, to replace the one he tossed in the river 36 years earlier.