NFL: Tom Brady (Football is a team sport, but it will be a long time before any player especially a QB wins 5 Super Bowls).
MLB: Babe Ruth (no debate what so ever. The greatest offensive player in history. MLB Career leader in Slugging %, MLB Career leader in OPS. He is 4th all time in runs scored, 3rd in home runs, 2nd in RBI's, all this despite being in the pitching rotation for the Red Sox for the first three years of his career. He was also a pretty good pitcher posting a career ERA of 2.28 and a winning percentage of .671. There is a misconception that the Babe was a big fat guy who could only hit home runs. But there wasn't a lot of video footage of him from his prime in the early 1920's. Most of the video footage and pictures we see of him today are from War Bond selling tours during World War II when he was in his late 40's. The Babe was an athlete, who could run, throw, hit, and hit with power.
NBA: Michael Jordan (6 rings, very athletic, and played both sides of the court).
NHL: Wayne Gretzky (his records will never be broken, but he played in an era of expansion where the talent pool was watered down and the game wasn't as fast and structured as it is today).
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