Original Desmond

Just finished watching the Great Debaters, also recently watched American Gangster. There's John Q and others

Has any actor been in more 'based on a real story' movies than Denzel ?

William Fuld

Not exactly the same as what you're asking, but here's a starter list of actors who have played real people many times:

http://forum.dvdtalk.com/showthread.php?t=412711

Count Dooku

Edward Herrmann?