Obviously this is a very general question, but who is THE most dominant sportsman/sportswoman/athlete at their sport of all time? There are many different sports so it's near impossible to single out one person who is better than everyone else overall, but we can surely name a few.
Don Bradman - Arguably (albeit I don't know anyone who would argue) the best player of all time. He ended his career with an average of 99.94, with the closest anyone has these days is around 57 or so. I honestly cannot see anyone ever having such a high average ever again playing as many games as Bradman did.
Michael Phelps - He entered 8 swimming events at the Beijing Olympics and won all 8 of them, convincingly. That is a pretty epic feat.
Roger Federer - I won't name every major tournament he has won, but I don't think it really needs explaining how consistently good this guy has been.
I'm sure there are others too. I don't know much about American sport, but obviously Michael Jordan was pretty good, as have been a few baseball players.