Cassius Marcellus Clay Jr. was born on January 17, 1942, in Louisville, Kentucky.
Clay made his professional debut on October 29, 1960, winning a six-round decision over Tunney Hunsaker.
He converted to Islam and became a Muslim after 1961, and eventually took the name Muhammad Ali.
By late 1963, Clay had become the top contender for Sonny Liston's title. The fight was set for February 25, 1964, in Miami Beach. Liston was an intimidating personality, a dominating fighter with a criminal past and ties to the mob. Based on Clay's uninspired performance against Jones and Cooper in his previous two fights, and Liston's destruction of former heavyweight champion Floyd Patterson in two first-round knock outs, Clay was a 7–1 underdog.
Ali then faced a rematch with Liston scheduled for May 1965 in Lewiston, Maine. and Ali Won the match in 2 minutes.
Ali prepared to fight Cleveland Williams in the Houston Astrodome on November 14, 1966. Ali dominated Williams, winning a third-round technical knockout in what some consider the finest performance of his career.
In March 1966, Ali refused to be inducted into the armed forces. He was systematically denied a boxing license in every state and stripped of his passport. As a result, he did not fight from March 1967 to October 1970—from ages 25 to almost 29—as his case worked its way through the appeals process before his conviction was overturned in 1971.
Ali defended his title against former heavyweight champion Floyd Patterson on November 22, 1965. Before the match, Ali mocked Patterson, who was widely known to call him by his former name Cassius Clay, as an "Uncle Tom", calling him "The Rabbit".
Ali won the fight in the 12th round through technical knockouts.
On August 11, 1970, with his case still in appeal, Ali was granted a license to box by the City of Atlanta Athletic Commission, thanks to State Senator Leroy R. Johnson.
Ali's first return bout was against Jerry Quarry on October 26, resulting in a win after three rounds after Quarry was cut.
Ali and Frazier's first fight, held at the Garden on March 8, 1971, was nicknamed the "Fight of the Century", due to the tremendous excitement surrounding a bout between two undefeated fighters, each with a legitimate claim as heavyweight champions.
The second of the three Ali–Frazier bouts, it took place at Madison Square Garden in New York City on January 28, 1974. Ali won in 12 rounds.
The defeat of Frazier set the stage for a title fight against heavyweight champion George Foreman in Kinshasa, Zaire, on October 30, 1974—a bout nicknamed The Rumble in the Jungle. Ali won by knockout in the 8th round.
Ali then agreed to a third match with Joe Frazier in Manila. The bout, known as the "Thrilla in Manila", was held on October 1, 1975
Following this win, on July 27, 1979, Ali announced his retirement from boxing. His retirement was short-lived, however; Ali announced his comeback to face Larry Holmes for the WBC belt in an attempt to win the heavyweight championship an unprecedented fourth time. The fight was largely motivated by Ali's need for money.
The fight took place on October 2, 1980, in Las Vegas Valley, with Holmes easily dominating Ali, who was weakened from thyroid medication he had taken to lose weight.
Holmes defeated Ali by 10th round TKO.
Despite pleas to definitively retire, Ali fought one last time on December 11, 1981, in Nassau, Bahamas, against Trevor Berbick, losing a ten-round decision.
Ali was hospitalized in Scottsdale on June 2, 2016, with a respiratory illness. Though his condition was initially described as "fair", it worsened, and he died the following day at age 74 from septic shock.