HeraldScotland looks back on his decades in the spotlight.
"Float like a butterfly, sting like a bee - his hands can't hit what his eyes can't see." (perhaps Muhammad Ali's most famous quote, said before fighting George Foreman in 1974).
1963: A supremely confident Cassius Clay holds up five fingers (above) in a prediction of how many rounds it will take him to knock out British boxer Henry Cooper.
"Who would have thought when they came to the fight
That they'd witness the launching of a human satellite?
Yes the crowd did not dream when they laid down their money
That they would see a total eclipse of the Sonny." (said before fighting Sonny Lipton in 1964)
1964: Cassius Clay rests during training for the world heavyweight title fight against Sonny Liston at Miami Beach, Florida. Ali went on to win the match, making him world heavyweight champion for the first time. Afterwards, he announced his conversion to the Nation of Islam, and his new name, Muhammad Ali.
"Cassius Clay is a slave name. I didn't choose it and I don't want it. I am Muhammad Ali, a free name - it means beloved of God, and I insist people use it when people speak to me and of me."
1965: Muhammad Ali spars with challenger Floyd Patterson during the World Heavyweight Championship fight. Clay won the fight, in Las Vegas, on November 25th, with a technical knockout in the 12th round.
"I ain't got no quarrel with the Vietcong. No Vietcong ever called me Nigger." (said when he became a concientious objector, refusing to fight in the Vietnam war, in 1966).
1971: Joe Frazier lands a punch during the Fight of the Century against Muhammad Ali. Though Frazier won on points at this meeting, Ali won their two subsequent bouts, including the Thriller in Manila in 1975
"It will be a killer and a chiller and a thriller when I get the gorilla in Manila."
1978:Muhammad Ali with his daughters Laila and Hanna (Getty Images)
"At home I am a nice guy: but I don't want the world to know. Humble people, I've found, don't get very far."
1972: Muhammad Ali during training for his fight with Al 'Blue' Lewis held in Dublin, Republic of Ireland in 1972.
"Boxing is a lot of white men watching two black men beat each other up."
2003: Muhammad Ali poses with daughter May May at a fundraising gala in Los Angeles.
"A man who views the world the same at fifty as he did at twenty has wasted thirty years of his life."
2009: Muhammad Ali with the British boxer Ricky Hatton, on a visit to Hatton's gym in Manchester.
"Friendship... is not something you learn in school. But if you haven't learned the meaning of friendship, you really haven't learned anything."
2009: Former boxing champion Sugar Ray Leonard joins Muhammad Ali after presenting him with an award in Ohio. (Getty Images)
"I done wrestled with an alligator, I done tussled with a whale, only last week I murdered a rock, injured a stone, hospitalized a brick. I'm so mean I make medicine sick."