Movie Characters You Could Never Imagine Anyone Else Playing

They'll probably cast some effeminate young British actor, like they do with every other role.

Eli Wallach as Calvera in the original Magnificent Seven

Bart was typecast, but honestly I couldn't imagine anyone else in those roles.

www.imdb.com/name/nm1075976/

I can think of a lot, but I'll narrow it to three:

Michael Keaton nailed Beetlejuice. We don't need any other tries.

Jack Nicholson was Jack Torrence of "The Shining." Weber had a good crack when they re-did it in a TV mini-series, but Jack is tough to top. Perfect mix of frustration, anger, and intelligence he rarely gets to share with the people he's usually interacting with.

Peter Cushing as Tarkin in "Star Wars." He's not a physically intimidating presence, but you could totally buy that he could be the guy bossing Darth Vader around. I think this is why the Hux character of the new movies (though I like the actor and how much it seems like he's trying) doesn't work. Cushing had this weird scariness. Christopher Lee and Hugo Weaving come to mind as comparable. Both of them have also played roles I'd be distracted to see played by another actor.

And because I haven't seen too many ladies mentioned...

Talia Shire as 'Adrian' in the Rocky series is a performance (in the first 2 at least) that doesn't get the attention it deserves. I couldn't see 'Adrian' as anyone else.

Sigourney Weaver as 'Ripley' in the first three "Alien" movies.  I think it's easy to forget how important this character was in establishing a heroine that could muscle up with Arnie and Sly.  And she didn't lose her emotional strength and become a cartoon character...until the 4th one...

Jamie Lee Curtis is also a badass who deserves her credit.  She was particularly awesome in "True Lies."  Arnold is such a huge presence, and she hung in there and delivered some of the best comedic beats of a movie built around this caricature of the 'Arnold' character.

Hugh Jackman as Wolverine is just perfect casting, he looks a lot like the Wolverine from the comics (minus being 5'4") and his American/Clint Eastwood voice suits the character perfectly.