Believe it or not, there are actually some athletes who are pretty good at acting!
Kareem tops the list for his remarkable turn in Airplane, which consists of him staunchly denying that he is Kareem Abdul-Jabbar until a little kid's criticism forces him to his own defense. But he's also up here for his excellent turn in one of the greatest martial-arts movies of all time, Game of Death, in which he takes on legendary actor/warrior Bruce Lee.
A former and incredibly successful bodybuilder, Arnold Schwarzenegger places #2 on our list not for his acting chops, which, though passable, aren't exactly Oscar-worthy. Instead, he charts because of his role in multiple emblematic and hugely profitable movies, including the Terminator series, Total Recall, and a bunch of others.
Again, Allen's starring role in He Got Game wasn't exactly Oscar-worthy. But it was entirely capable. And the fact that he took on a leading-man character named Jesus Shuttleworth in a Spike Lee joint opposite Denzel Washington at the age of 23? That takes incredible guts.
Jim Brown was in The Dirty Dozen. That should sum it up.