I think a lot of people are subconsciously picking their favorite roles for the actors, or the ones for which movies they've seen, and not the ones that the most people recognize the actor from... especially if its a role from a movie people may not have seen and still recognize the actor!
For example, Tom Cruise has been in four Mission: Impossible films, but when you say "Tom Cruise" to a random person on the street the first movie they think of is Top Gun, 90% of the time. Only younger people would think M:I, which is fair but not everyone is young.
That being said:
A) Tom Hanks - Forrest Gump
B) Mel Gibson - Braveheart
C) Arnold Schwarzenegger -Terminator
D) Sylvester Stallone - Rocky Balboa
E) Bruce Willis - Die Hard
F) Tom Cruise - Top Gun
G) Will Smith - Independence Day
H) Robert Patrick (other than the T-1000) - Too bad, I'm saying T-1000
I) Harrison Ford - Indiana Jones
J) Richard Gere - Pretty Woman
K) Robin Williams - Aladdin (it counts)
L) Robert DeNiro - Taxi Driver
M) Jim Carrey - Ace Ventura
N) Samuel Jackson - Pulp Fiction
O) Jack Nicholson - The Shining
P) Morgan Freeman - Shawshank Redemption
Q) Danny Glover - Lethal Weapon (yeah, not as popular as Mel Gipson.)
R) Joe Pesci - My Cousin Vinny
S) Eddie Murphy - Beverly Hills Cop
Bonus Question: Which of the 3 actors above are most famous for their overall work/roles?
Tom Hanks and Arnold Schwarzenegger are the clear 1 and 2, and 3 is a toss-up. I'd go with Harrison Ford or Tom Cruise, but an equal case could be made for many of them.