The Independent tasked five of its top sports writers to come up with their top pick each to add to the debate.
OLGA KORBUT (GYMNASTICS)
By Kevin Garside
The winners and losers are determined by facts, but our attachment to them is essentially emotional. We remember not necessarily the fastest, strongest, longest, etc, but the ones who left an impression. Mexico is too far back for this observer save for the gloved salute of two Americans during a medal ceremony. I would have to Google them to give you their names (to save you doing it, here you go: Tommie Smith, John Carlos), but as a nipper in the North-west of England I recall the power of the moment.
Munich was a different matter, the first Olympics to gain my full attention. Two names will forever be associated with it; Mark Spitz and Olga Korbut. Spitz the moustachioed missile was not hard to like. Handsome, athletic, strong, he conformed not only to the Olympian ideal but to the requirements of the matinee idol. He was American, which meant he was slotting into the stereotype forming in the imagination of a young lad of American supremacy in all things bar football and cricket. Seven golds was in my infantile mind the going rate for someone who looked like he did.
Korbut on the other hand was a revelation. She came from a place where the bad guys lived. The Soviet Union was a grey expanse of force-fed dogma, where people lived in the same poky flat, wore the same clothes and queued for bread. I knew this because, in my memory at least, that was the imagery of the television news bulletin in Seventies Britain, where bad stuff in Moscow vied with bad stuff in Northern Ireland to make the headlines.
And then on to the Olympic floor in Munich stepped a tooth fairy in a red leotard and bunches. There was nothing of her yet she flung herself across that mat, defying the laws of physics, and of socialisation, springing, jumping, twisting and in the end dancing into every living room in Britain. By the time she cocked her wrist at the end of her programme, the nation's collective mouth was gaping at the wonder of what they had just seen. She is best remembered for her technical brilliance on the beam, but it was the flourish on the floor that opened these eyes to the idea of colour and expression behind the Iron Curtain.
Forty years on, the boy now a man and the elfin child a divorced resident of Arizona, crossed on the stairs in a BBC studio in the Olympic village. She was preceded by fellow Olympic pundits Michael Johnson and John McEnroe, heavyweight traffic in the company of most, but lightweight in hers. At least that is how it is in my sporting hierarchy. There she was, looking a little confused in the post-show chaos that invariably follows, trying not to trip over camera cables. I think she thought I was the driver of the buggy that would take her off the site. If only she had asked.
FANNY BLANKERS-KOEN (ATHLETICS)
By Chris McGrath
The gauge of Olympic greatness is not always set by other champions; nor even by the inexorable opposition of the years, which made Sir Steve Redgrave or Birgit Fischer such miracles of longevity. Fischer won eight gold medals, over six Olympics, but the fact is she - in common with every female achiever at the Games, through to Heather Stanning and Helen Glover yesterday - was in some degree indebted to the pioneering Fanny Blankers-Koen.
This remarkable Dutchwoman overcame an obstacle as invisible as time itself, but still more insidious. For while athletes can measure themselves against time in the record books - whether by stopwatch, or date of birth - the spectre of prejudice had haunted countless generations.
So even if Michael Phelps, with his diversity of opportunity, does not quite gain the laurels as greatest Olympian, at least the stage remains unchanged. For it was in London that Blankers-Koen dismantled so many of the barriers before her sex. Women had not contested the Games at all until 1928, and Blankers-Koen arrived from Amsterdam in 1948 as a 30-year-old housewife and mother of two, duly ridiculed or resented.
She proceeded to match the four gold medals won by Jesse Owens at Berlin 12 years earlier. In the meantime, of course, she had lost her own prime to the war. Having set her first world record in 1938, at 100m, she would be denied an international stage during the German occupation - nonetheless posting six world records in disciplines as varied as high jump, long jump, sprint, hurdles and relay, all the while vilified for ostensibly neglecting her young son.
After a winter of famine, she gave birth to a daughter in the year of liberation, but soon resumed what now seems a hopelessly dilettante training regime with a view to London. She was preceded to the Games by abusive letters and articles, telling her that no ageing mother had any place wearing shorts on a cinder track.
Confined to a maximum of three events, Blankers-Koen sat out the long and high jump, despite holding the world record in both. And she duly won gold at 100m and 200m, hurdles and relay - still a record haul for any woman, in track and field, at a single Olympiad.
In 1999, Blankers-Koen was named the female athlete of the 20th century by the International Association of Athletic Federations. Her greatest reward, however, was as intangible as the pervasive bigotry she overcame: legitimacy.
JESSE OWENS (ATHLETICS)
By James Lawton
If you go beyond the great mountain of gold created by Michael Phelps, if you acknowledge his superb achievement in winning more medals than any rival, it is not so difficult to look elsewhere for the greatest of Olympians.
Your search, the feeling is here, takes you back to the Berlin Olympics of 1936 and Jesse Owens, a young black man born to grinding poverty in Alabama, who infuriated Hitler by winning four gold medals with a running, jumping assault on his master-race theories.
In fact, Hitler's confidant Albert Speer later reported that in his rage the Nazi leader argued that people of Owens' "type" should be banned from sports competition because of their "unfair" advantage.
Part of Hitler's ire, no doubt, was that Owens won his fourth gold in the men's 4x100m relay only because the Nazis had pressurised the US team to drop a Jewish-American member of the team.
Phelps' total of 19 medals represents superb performance, but they have been gleaned from three Olympics. Owens had just one opportunity and won gold in the 100m and 200m, the long jump and the relay. It was the equivalent of a perfect 10 and its meaning remains as vivid as the foot-stamping of Hitler.
Owens, like so many of his race, was not exactly embraced by white America. At one point in his career, he ran against horses to eke out his living, but what no one could ever dispute was the force of his achievement, and what it might have led to if the Second World War had not wiped out the next two Olympics.
"I was told it was degrading for an Olympic champion to get involved in professionalism but I asked what I was supposed to do. I had four gold medals but you can't eat four gold medals," Owens said.
Earlier, as a college student, he broke the world record for 100 yards and, in one hour and 45 minutes of collegiate sport in Michigan, he broke three world records and equalled another. His long jump record of 26ft 8 1/4 inches lasted 25 years.
Supporters of the Phelps case can cite so many instances of brilliant, world-record-breaking performance. They can point to the certainty of his efforts in Athens and Beijing, where he won, respectively, six and eight gold medals, and here in London the big man from Baltimore has fought with grit - and considerable grace - against the tyranny of the years.
Owens was never challenged by the years but the circumstances to which he was born - and the handicaps which came with the colour of his skin. His family - he was one of 10 children - left Alabama for the steel mills of the north. His fate might also have been the life of a factory worker at subsistence level.
However, he recognised early a "rage to run" , in the Olympics which were supposed to showcase the ascendancy of the Aryan race, he produced a series of perfect performances. He was the man of those Olympics and, many will always believe, he captured the ages.
EMIL ZATOPEK (ATHLETICS)
By Simon Turnbull
How many Olympic golds does it take to achieve Olympic greatness? How long is a piece of string?
Determining the greatest Olympian of all time is a subjective question, not simply a matter of mathematics. When set against Michael Phelps' Fort Knox collection of 15 golds, Emil Zatopek's four do not stack up. But then the hat-trick that the great Czech soldier achieved at the Helsinki Olympics in 1952 was unprecedented and remains unmatched in the history of distance running.
Winner of the 10,000m gold at the London Olympics in 1948, Zatopek successfully defended that title in the Finnish capital, then won the 5,000m and made a last-minute decision to compete in the marathon - the first of his life. After 10 miles, he turned to Jim Peters, the world record-holder and favourite, and asked: "Is this pace too fast?" Peters, an optician from Essex, replied: "No, it's too slow."
At which point Zatopek - hardened by a punishing training regime that included running through the woods around Prague in army boots - upped the pace. He proceeded to win in Olympic record time. The exhausted Peters failed to finish.
To qualify for consideration as the greatest Olympian of all time, however, requires more than mere athletic dominance. It requires the kind of golden spirit that Zatopek showed when the Australian Ron Clarke visited him in Prague in 1968.
Clarke suffered misfortunes in the Olympics, collapsing in the high altitude at the 1968 Games in Mexico. When Zatopek dropped him off at Prague airport, he handed him a small parcel and said: "Not out of friendship but because you deserve it."
When his plane was airborne, Clarke retired to the privacy of the lavatory and unwrapped the box. "There, inscribed with my name and that day's date, was Emil's Olympic 10,000m gold medal," he said. "I sat on that toilet seat and wept."
MICHAEL PHELPS (SWIMMING)
By Robin Scott-Elliot
Yesterday Michael Phelps celebrated becoming the most decorated Olympian in history by swimming the heats of the 200m individual medley. That is what makes his 15 gold, two silver and two bronze medals - with more to come over the next three days - a priceless collection. Swimming is a gruelling, relentlessly demanding sport, whether in or out of competition.
This is Phelps' fourth Games. In his first at 15 he finished fifth in the 200m fly. A dozen years later in the same event he equalled Larisa Latynina's record of 18 medals. An hour later it was 19 with another 200m ticked off, this time the freestyle relay.
The distance is part of the story, and the number of times Phelps covers those distances. Olympic events require three swims to claim gold. In the relays Phelps will compete only in the final, but to achieve what he did in Beijing is a triumph of endurance as well as athletic ability.
In 2008, Phelps swam for eight successive days, up to three races a day, 15 races in all. It was a programme from hell that took him to sporting heaven. Of those, the 200m fly and the 400m individual medley are particularly harsh on the body. Ahead of the Games the weight of opinion was that an attempt to better Mark Spitz's seven golds was next to impossible (not least by Spitz himself) given the schedule and the higher level of competition. But Phelps did it - eight golds from a single Games, a feat that in itself makes him the greatest.
Four years earlier in Athens aged 19 he took six golds. Those came amid fierce competition, and that is another element that elevates Phelps' achievements. He has triumphed in an era that has seen him surrounded by high-class swimmers; Ian Thorpe, Ryan Lochte, Laslo Cseh, Pieter van den Hoogenband, and at a time when the sport has become faster and faster. He has set the pace.
Swimmers do not have the longevity afforded the best in some other sports - look at how Thorpe's comeback ended in failure at 29. Phelps is now 27, and there is not a swimmer who does not suffer from shoulder pain and widespread wear and tear, yet he is still collecting medals. He is not the Phelps of old, but he is still likely to finish London 2012 with at least four medals and an overall total into the twenties. Phelps may not have the wider impact, or importance, of a Jesse Owens, or the longevity of a Steve Redgrave, but in terms of sporting achievement, he's without equal.
- THE INDEPENDENT, AP and HERALD ONLINE