A) Tom Hanks - Woody
B) Mel Gibson - Deranged Antisemite
C) Arnold Schwarzenegger - The Terminator
D) Sylvester Stallone - Rambo
E) Bruce Willis - John McClane
F) Tom Cruise - Ethan Hunt
G) Will Smith - Agent J
H) Robert Patrick (other than the T-1000) - Mr Lisp
I) Harrison Ford - Han Solo
J) Richard Gere - Edward Lewis
K) Robin Williams - The Genie
L) Robert DeNiro - Travis Bickle
M) Jim Carrey - Ace Ventura
N) Samuel Jackson - Zeus (Die Hard 3)
O) Jack Nicholson - Jack Torrance
P) Morgan Freeman - Red (Shawshank Redemption)
Q) Danny Glover - Roger Murtaugh
R) Joe Pesci - The Wet Bandit
S) Eddie Murphy - Axel Foley
Bolding where I differ from the first response. You might notice that I'm privileging roles in kids' movies somewhat. My impression is that far, far more people have seen Home Alone, for example, than have seen Raging Bull or Goodfellas.
The three most famous are Hanks, Ford and Schwarzenegger. The former two were both, at respective times, the number one box-office draw in Hollywood and the latter was independently famous (albeit in a fringe community) prior to acting and has also entered politics - a triple threat, fame-wise.
Edit: I see the OP has specified movie roles only, so I've changed my response for Will Smith from the Fresh Prince to Agent J and for Robert Patrick from John Doggett to Mr Lisp (Spy Kids).