There have been, and are, many actors who don't really act. They just play themselves in different roles. In many cases this isn't necessarily a bad thing. Clint Eastwood comes to mind. Oh, he's tried to expand his range, and I like most of his movies, but he's really the same character in most of his movies. On the comedic side, Jim Carey is another one. He's shown some range, but many of his movies are the same act. But, at least he's funny.
Then there are those who can't seem to be anything but the same character over and over and over again . . . and it's annoying. For me, Will Ferrell is the worst offender. Adam Sandler is another one. But in his case, his movies are just retarded more than anything. Getting close is Jack Black.
Another one? Ben Stiller. And I'm not the only one who thinks so:
I Hate Ben Stiller.
Who annoys you?