I believe Wilt Chamberlain is the greatest individual athlete in the history of American team sports--and it's not even close.
Let's look at some of his most amusing numbers. These are taken from various sources, such as the back of a '96 Topps Stars card, NBA at 50 edited by Mark Vancil, http://www.basketball-reference.com, Who's Better Who's Best in Basketball? by Elliot Kalb, and whatever is sitting around in my memory from who knows where.
1. In his entire career, he never once fouled out of a game.
Think about that. Think about the body control such a feat requires, particularly for a center.
2. In one season, he averaged 48.5 minutes per game.
You have to look at that number and think about it for a second. Seriously. A legitimate argument could be made that Wilt has more stamina than any athlete on record. He also has the NBA record for career minutes per game (45.8). You could make the argument that Wilt's rebounding and scoring numbers are inflated because he played in a run-and-gun era that had way more team shots attempted per game. But that also means that Wilt averaged more than a complete game during the run-and-gun era, and he set the record for minutes-per-game in a run-and-gun era. And according to NBA at 50, Wilt also had 47 consecutive COMPLETE GAMES.
3. He's the only NBA player to have led the league in points/game, rebounds/game, and assists/game.
Is this an argument for Wilt as the most versatile basketball player ever?
4. He has the record for points in a game (100) and points per game in a season (50.4).
5. He has the record for rebounds in a game (55), rebounds per game in a season (27.2), and career rebounds per game (22.9).
That 55 came against Russell. He also has the 2nd, 3rd, 5th, 6th, and 7th highest rebounding average seasons (though I actually believe Dennis Rodman is the greatest rebounder ever).
6. He has the highest points per game in a season (50.4), and the second (44.8), and the third (38.4).
The next highest is Elgin Baylor, who averaged 38.3 in 48 games. That means the next best scorer to Wilt (who also played in the same run-and-gun era) has a career high scoring average that is 76% of Wilt's career high, but that Wilt actually has two other seasons better than that. Michael Jordan's highest scoring average in a season was 37.1, which Wilt beat in his rookie year (37.6). Wilt also has more 50 point games than anybody (122 to Jordan's 37, and Wilt once had 45 in one season), 60 pt. games (32-4), and 70 pt. games (6-1).
When I look at these numbers, I cannot help but think he is the greatest basketball player ever. Certainly arguments can be made for Bill Russell (you can't argue with winning, but 11 championships is a team achievement), Jordan (I think the greatest non-center), Magic, Bird (unquestionably the greatest forward), and Kareem (a ridiculous career when you take a hard look at it: 6 MVPs, 6 championships, more points than anybody ever). Maybe you could make an argument for Oscar Robertson, to (he would compete with Magic as the greatest all-around guard).
But Wilt's records in his sport are so far superior to any #2 in his sport, and his ridiculous feats of athleticism and stamina make him the greatest in any sport.