Now, aged 63, Muhammad Ali is becoming a designer. Having worked with the sporting goods giant Adidas on their "Impossible is Nothing" advertising campaign last year, the greatest boxer ever to grace the ring has put his name to a new range of clothing which retraces the steps of his monumental career.
"Throughout my life," says Ali, "I have pushed the boundaries of what is expected. I am excited about my new partnership with Adidas as it will inspire in a completely new way, not only my existing fans, but a new generation as well." The Adidas collection certainly taps into an increasing desire in the general public to be involved with the Ali brand. If anything, Ali has become more popular as the years have gone on, as films such as When We Were Kings - documenting his famous Rumble in the Jungle of 1974 - and Ali have reached out to people too young to have seen Ali fight.
Adidas clearly feel they have struck gold. Erich Stamminger, the CEO of Adidas America, was effusive: "We at Adidas are honoured to have had the opportunity to work with Muhammad Ali on this line. Ali by Adidas pays tribute to the legacy of the greatest sports icon of all time."
Fashion design, though, represents a remarkable renaissance for a man whose life has been shattered by motor neurone disease - a direct result of his extended career in boxing. His direct involvement with creating the line of clothing - short of creating the iconography and history behind many of the items - must have been minimal. But top companies know an earner when they see one, and the Muhammad Ali line has every chance of being just that.
Comprised predominately of sporting leisurewear, the collection has a retro feel, with many of the pieces alluding specifically to Ali's 1974 fight with Foreman in Zaire. Items such as the white robe and shorts, replicated from that famous night in Kinshasa, will become a must-have for Ali fans.
In fact, to look at the Adidas Ali line, you might be forgiven for thinking that The Rumble in the Jungle was the only fight Ali ever had. The sales patter, too, is uniformly upbeat. Ali is quoted as saying: "I'd like to be remembered as a black man who won the heavyweight title and who was humorous and who treated everyone right. As a man who never looked down on those who looked up to him and who helped as many of his people as he could - financially and also in their fight for freedom, justice and equality."
A few of the women in Ali's life might have a thing or two to say about whether the boxer "treated everyone right". And it would be interesting to see Joe Frazier's reaction when Ali claims that he "helped as many of his people as he could". The light-skinned Ali famously called Frazier "a gorilla", in frequent attacks that had distinctly racial overtones.
Many people will feel that where Muhammad Ali is concerned, such quibbles are misplaced. The man was and is a legend - witty and garrulous outside the ring; graceful and brutal within it. He transcended sport in a way that no other athlete has achieved before or since.
Muhammad Ali has, quite rightly, built a potent mythology. And that mythology is precisely what fans will be thinking of when they pull on their "Float like a butterfly, sting like a bee" sweatshirt.
The 'Ali by Adidas' range, part of the A/W 2005 Adidas Originals collection, is available from November 2005. Stockists: 08702 404 204
Perfect pitch: the stars behind the brands
Who? The hulking Fran Cotton was something of a cult rugby union hero for both England and the British Lions. In the game's amateur days during the late 1970s and 1980s, he played alongside his more elusive fellow international, Steve Smith. On the pitch they were completely different performers. Off it, they formed an unbeatable team.
Winning Formula? Cotton and Smith were often to be found at the bottom of a muddy ruck. But now, having set up a rugby and leisurewear clothing company called Cotton Traders when they retired from playing, they have come up smelling of roses. The company has a turnover in excess of £50m a year and employs more than 600 people across the world.
NIKE AIR JORDAN
Who? Michael Jordan was the greatest basketball player ever, taking the Chicago Bulls to six NBA championships in the 1990s.
Winning formula: In 1985, Jordan put his name to the world's most popular trainer. Nike Air Jordan, with its distinctive air cushion, traded on Jordan's ability to stay in the air for extraordinary lengths of time. It sold more than a million pairs in its first year, and has remained Nike's best-selling basketball shoe ever since. The Jordan brand soon spread to all aspects of sportswear.
THE PREDATOR FOOTBALL BOOTS
Who? Craig Johnston was born in South Africa, raised in Australia and enjoyed success as a player with both Middlesborough and Liverpool in the 1970s and 1980s, scoring a goal in Liverpool's 1986 FA Cup final win over Everton.
Winning formula: It would be Johnston's time as an apprentice for Middlesborough that would pay dividends after he retired. He started to design football boots with Adidas, developing what would become the world's best-selling boot, The Predator. Johnston has since designed The Pig, which can be bought as an extra-grippy boot or a cover that fits over conventional footwear. His products are worn by David Beckham, Zinedine Zidane and Jonny Wilkinson.