3. Jack Black
Jack Black's contrived comedic persona, which usually depends on fat jokes and musical interludes, is beginning to wear thin. In his more understated roles in Shallow Hal (2001) and the saccharine romantic comedy The Holiday (2006), he's very watchable, but at some point in the last few years we lost interest in the caricature we loved in School of Rock (2006) and Kung-Fu Panda (2008). Since then, Black's made a number of duds. Black can make a good job of a more complex comedic part, so he falls squarely into the category of actors whose cartoonish personalities onscreen just aren't working anymore. It's most evident in the dire Year One from 2009, in which Black's overacting can't really compensate for just how terrible the film is.