Which actor, while not resembling the person being portrayed pulled off a believable performance?

Speaking of Kevin Kline – he did a great job in Pirates of Penzance (musical) IMDB link. I didn’t even know he could sing.

@elbanditoroso -Me either. I liked him best in “A Fish Called Wanda”.

I was going to say Steve Buscemi in Boardwalk Empire, but then the character he’s playing (Nucky Thompson) is a fiction that’s only loosely-based on the real person (Nucky Johnson).

John Lithgow as Churchill in The Crown. How, at 6’4” tall he managed to so convincingly portray such a short man was amazing.

Billy Bob Thornton looked nowt like Santa.
Mel Gibson miles away from William Wallace
The lead camel in Lawrence of Arabia looked fake, like two guys in a camel suit.

David Spade. Impersonating George Bush Sr.

Bradly Cooper in the stage play of The Elephant Man.

Ryan Reynolds as Pikachu.

Aidan Quinn, who played the police Captain on Elementary, also played a very believable Beatle, Paul, in a movie called Two of Us.