8. Orlando Bloom
Aside from a few small appearances in British shows like Casuality, Orlando Bloom was virtually unknown until he was cast as Legolas in The Lord of the Rings trilogy, propelling him to overnight fame, and leading to him also starring in the Pirates of the Caribbean franchise as Will Turner. All he proved in these films, however, was that he had the
look, but not the talent; his obnoxious delivery of lines and incredibly forgettable personality made for some of the more awkward moments in both the Rings and Pirates series, and so it wasn't too much of a surprise that he ended up being written out of the latter franchise alongside Keira Knightley. Compounding this is his CV since; he's starred in a small number of indie productions, but hasn't exactly scored a big success since leaving those franchises. He's reported to appear in the third and final Hobbit film, There and Back Again, but I imagine after he's done milking that gravy train he'll return to the obscurity he's suffered for the last half-decade.