“He was entertaining and when he was younger he was always mouthing off. But it was part of his schtick. He made [boxing] part theatre, part dance and all power”
Bill ClintonFormer US President
He also made plenty of headlines outside of the ring with his sharp words and refusal to take part in the Vietnam War.
But Clinton believes his fellow American's legacy will be the way he got the whole world talking about boxing again in the 1960s.
"People had moved away from boxing. It was a huge deal in America in the 1940s and 1950s and then they wrote it off," he told BBC Sport boxing commentator Mike Costello.
"Then here comes Muhammad Ali, first as Cassius Clay, looking like a ballerina in the boxing ring - reminding people it was a sport.
"He made it exciting and meaningful again. He was entertaining and when he was younger he was always mouthing off. But it was part of his schtick.
"He made it part theatre, part dance and all power."
MUHAMMAD ALI FACTFILE
Born Cassius Clay on 17 January 1941 in Louisville, Kentucky
Wins Olympic light-heavyweight gold
Beats Sonny Liston to be crowned world heavyweight champion
Changes his name to Muhammad Ali after joining Nation of Islam religious movement
Refuses to step forward in US Army induction for Vietnam service
Suffers first professional loss in 'The Fight of the Century' against Joe Frazier
Regains title with shock win over George Foreman in fight billed as the 'Rumble in the Jungle'
Beats Frazier in the 'Thriller in Manila' to take crown for an unprecedented third time
Fights for the final time in defeat by Trevor Berbick
: Diagnosed with Parkinson's Disease
: Lights Olympic flame at opening ceremony of Atlanta Games
Voted BBC's Sporting Personality of the Century
Ali risked his glittering career, and his reputation, to oppose
the Vietnam War
. He refused to serve in the US Army when he was called up for service and was subsequently arrested for committing a felony.
Boxing authorities suspended his licence and stripped him of his titles before he was found guilty of the offence after a 1967 trial. The US Supreme Court reversed the conviction four years later.
"It could have destroyed him but it didn't - because people realised he had been very forthright and he was prepared to pay the price for his convictions," said Clinton. "On balance he won more admirers than detractors."
Ali's success helped break down racial barriers in the US and create the path which eventually led to President Obama's election in 2008, according to Clinton.
"All those people from the Civil Rights years and also every African-American who did everything that destroyed the old stereotypes have helped," said Clinton, 65.
"There was nothing inferior about Ali - he was superior on merit without regards to his race when it came to what he loved.
"All this stuff played a role. Society changes slowly, like icebergs turning in the ocean. Sometimes great symbolic events affect changes of consciousness of a whole country. Ali reflects a lot of that."
Sir David Frost
, who famously verbally sparred with the boxer during television interviews at the height of his fame, believes Ali touched the hearts of millions with his words.
He said: "Over the years Muhammad Ali spoke with peace. Not just for boxing but peace in general.
Mike CostelloBBC boxing commentator
Ali was the primary reason I took up boxing. I wonder how many more youngsters across the globe pushed open a gym door for the same reason
"Although he spoke in this war-like rhetoric, it was already clear that the man beyond that rhetoric was a warm and friendly and peaceable man.
"He became the most famous man in the world for a long time. He's not far off it now even."
Former British and Commonwealth heavyweight champion
fought Ali in 1973 and 1975, losing on points on each occasion. He told
BBC Radio 5 live
Breakfast: "It was a great pleasure to fight him on both occasions.
"He was more of an athlete than a fighter. He was a highly intelligent athlete, who utilised every inch of the boxing room."
insists the world will never see another boxer like Ali, whom he believes put "boxing on the map".
"He paved the way for boxers like myself to want to go into boxing and make a living for themselves," said Bruno.
"We're grateful we had Muhammad Ali to inspire us."
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