Whoa! We argue here all the time about whether one can reasonably rate props versus 8-men (much less stand-offs), or current players versus retired but still very much alive ones. Now we are to do this across sports? I'd probably have said Abebe Bikila, the Ethiopian marathoner who won two gold medals (including the classic 1960 race which he ran barefooted)., but he alas is dead. In 1972, he qualified for the Olympics in Archery, after a tragic auto accident that left him paraplegic, but the Ethiopean team in the end did not make it to Munich in time for his event. So Pal Szcheres, the Hungarian fencer. He medaled in both the standard Olympics (1988), then 6 times in the ParaOlympics, 1992-2008). I know people will say Michael Jordan, or Ali, or maybe some amazing gridiron player, but life is pretty easy when you get all the breaks. The combination of skill, commitment, and mental toughness needed to come back form a catastrophic injury to again become a world champion? That is very special my friends. That is the sort of thing, I will call out as the GREATEST. Mark L

- The pound-for-pound best athletes in the world. ... and his save percentage was the best ever

Mccaw, messi. Phelps, Usain Bolt, Dawn Fraser, brock lesnar Each to their own