I'm also thinking Bo Jackson, but Deion Sanders was faster...
I don't think any mountaineer will ever be more accomplished than Reinhold Messner.
Ted Williams was one of the best baseball players who has ever lived, but I think it was more of a combination between his almost unbelievable vision and hand/eye coordination, rather than all around athleticism. The fact that he was a good hunter and fisherman was definitely a plus!
And Ted Williams spent some of his prime MLB years at war.
Set many International fishing records.
