George Clooney. I think he's a great guy, very stylish and handsome, but I've always found his acting to be just playing himself, never convincing in whatever role he's playing.
In one of the books behind the Star Trek movies, Nicholas Meyer talks about directing Shatner. He says some actors are *actors*, and some are "stars", and Shatner was a star :-) The scene where they take over Khan's ship to drop its shields, and Kirk's line "Here it comes" - Meyer wanted it delivered subtly, without any swagger or boasting. He said it took dozens of takes, and he only got the take he wanted when Shatner got tired of the multiple takes.