Just a question: How do you guys define "great" athletism? IMO a great athlete doesn't only define himself by talent or abilities that make him stand him out from others but also by continuous improvement and the will to go until the maximum to get even better.
Don't get me wrong: Ronaldo and Maradona were great footballer but all time great athletes? Certainly not, especially not Maradona who basically did everything possible outside the pitch to limit his physical abilities. I'm no personal fan of him but if there's one footballer who deserves to be here, then it's CR7.
Anyway, although I certainy will miss some great names here, here's my top 15 (without any special order):
Daley THOMPSON (IMO the greatest athlete ever who both competed and dominated in the most challenging sports discipline, I'm surprised that no one mentioned him here before)
Michael PHELPS
Carl LEWIS
Emil ZÁTOPEK
Eddy MERCKX
Usain BOLT
Martina NAVRATILOVA
Cristiano RONALDO
Michael JORDAN
Ole Einar BJØRNDALEN
Wayne GRETZKY
Muhammad ALI
Michael SCHUMACHER
Jim BROWN
Roger FEDERER
But as I said above there would be plenty of other names who could be mentioned here.