I am goling to have to go with Clint Eastwood here.He has been a great on screen representative for S&W.Why?He really likes them.
I will admit that I have not read every one of the post responses here ,so this may have already been mentioned.If so,my apologies.
If anyone remembers "The Gauntlet" you may also remember that Eastwood was using either a Mod.19 or 66(I can't remember which myself

). If you look closely at the scene where he was in the phonebooth you will see that it was one of the 2 1/2 inch square butt versions,very rare.
It has been said that this was one of the production models and not a converted one,and this particular revolver was actually Eastwood's own personal gun. I saw an article on that several years ago.
Then we have the Big .44 in the Dirty Harry flicks,along with the Bloodwork gun,named because of the movie of the same name.
I think he best typifies an S&W revolver fan in his on screen persona.