4. Ty Cobb
Ty Cobb may have been the best baseball player of all-time, but there is little doubt that he was the dirtiest. Cobb was the leading vote getter on the inaugural Hall of Fame ballot (above Babe Ruth), set 90 MLB records during his career, and still has the high career batting average (.367). But Cobb's legacy as a great player is overshadowed by his style of play and off-field issues.
Cobb was known for sliding with his spikes up when he stole bases, when he sharpened to intentionally cause fielders to bleed, but those were the smaller of the Cobb controversies. He was a known fighter on and off the field -- one time he fought umpire Billy Evans after a game. The fight was stopped only after Cobb had pinned Evans and began choking him.
Cobb was also openly racist, once having stabbed a black night watchman, who intervened after Cobb had slapped a black elevator operator for "being uppity."
On another occasion, after six innings of persistent heckling, Cobb jumped into the stands and attacked the fan bothering him, Claude Lueker, who happened to have no hands. As Cobb beat the man, onlookers shouted at Cobb to stop, to which Cobb reportedly replied, "I don't care if he has no feet!"
Cobb was accused of being involved in a scheme to fix a game (for his team to win). This incident eventually led to Cobb retiring from baseball in November 1926, but by January 27, 1927, Cobb was reinstated and finished out his career with the Philadelphia Athletics.
Putting together these stories, it's no surprise that Cobb is remembered as much for his infamy as his greatness.