Lee J. Cobb was totally unlike what Miller had in mind for the lead role of Willy Loman in Death of a Salesman. Miller himself has said so, but he created the role on Broadway and made it his, so he’s pretty much the default image (even though they got Fredric March for the film version).
Miller himself later said, when Dustin Hoffman took the role on Broadway, that he was more of what he had in mind.
Johnny Depp in Sweeney Todd. He was too young, too slight, too pretty and not a strong singer - but by the end he had won me over anyway. Unlike HB-C who faced the same problems and never really became Mrs Lovett (a role definitely played by Angela Lansbury IMHO).
In an odd way, Keanu Reeves as John Constantine. Aside from the fact that the entire movie was completely transplanted and kept much fo the feel, but none of the detail of the original, Keanu was surprisingly good as a depressed, sick son-of-a-gun with few redeeming qualities, but who steps up to be the hero anyway.
Yeah, it’s weird. I love Constantine the film but hate the liberties they took with the characters. It totally stands on its own, but is a pretty faithless translation of the comic book John Constantine.
Anne Hathaway in Rachel Getting Married. Now, she’s branched out a bit, but at the time, she was the sweet girl-next-door. Ella Enchanted, Princess Diaries, etc. had been her previous experience, but in Rachel, she was disturbed, addicted, etc.
Also, Will Ferrell in Stranger Than Fiction. He’s usually the jerk or the man-child, but in this movie, he was subdued, confused, frightened… and he pulled it off.
And while we’re talking about comedians who can pull off drama, I loved Dane Cook as Mr. Smith in Mr. Brooks. He was so sly, so manipulative, so disturbed. Totally unlike his stand up where he’s flailing around as a goofy idiot.
In the Sookie Stackhouse (“True Blood”) books, Bill Compton was a Confederate soldier with young kids, which would put him in his mid-to-late 20s. **Stephen Moyer ** is 40-something, not to mention a Brit. When he first appeared on screen, it was jarring because he wasn’t what I pictured, but I’ve come to love him in the role.
Olivia Newton-John was way too old to play a high school senior, yet I can’t imagine anyone else in the role of Sandy in “Grease”
The part of Gareth Keenan in the UK “The Office” series was written to an overweight yet vulnerable guy. It took awhile for Gervais and Merchant to realize that young, skinny Mackenzie Crook would be the right choice.
And, of course, we have the fact that Angel on “Buffy” had a face of an angel. David Boreanaz was way too beefy for the role, but he worked for me.
Daniel Craig as James Bond. Everybody was saying he was totally wrong for Bond, he’s not good looking enough, you can’t have a blond Bond, he’ll be terrible, etc., until Casino Royale came out and squelched the naysayers.
Randle Patrick McMurphy is one of my favorite fictional characters, and my personal image of him was so strong, when Jack Nicholson portrayed him in the movie version of One Flew Over the Cuckoo’s Nest, I was disappointed by his portrayal. Eventually, I came to accept that there was no one right way to play the role, and that it was a spectacular performance, but it had a lot of prior imagery to overcome before I could admit that.