Tom Hanks
I have a hand full of actors that could make the list, but im going to have to give the nod to Mr Hanks.
Almost any film which places him in a starring role is sure to be a hit. I would have a hard time naming a film of his that didnt touch me on an intellectual or emotional level. One of the purposes of cinema is to do just that. From
Big to
Saving Private Ryan... from
Cast Away to
Forrest Gump.
Either Hanks is a supremely skilled and talented actor, or he is supremely skilled at selecting roles which best pair with his capabilities. Either way, what he puts up on screen works.
EDIT: @ Steelhead... i have always appreciated Eastwood as an actor, but i think i have grown most fond of him as a Director