10 Best Actor Replacements In Movies

10. Paul Dano - There Will Be Blood

Paul Dano in Paul Thomas Anderson's epic period drama There Will Be Blood is an especially interesting case given that Dano was already cast in the film in the small role of Paul Sunday.

The part of Paul's preacher brother Eli was originally played by Kel O'Neill, who was fired two weeks into shooting.

Though rumours initially indicated that O'Neill was intimidated by co-star Daniel Day-Lewis' intense method acting, this was ultimately dismissed by O'Neill, Anderson, and Day-Lewis.

All the same, Anderson decided to replace O'Neill with Dano himself, in turn changing Paul and Eli Sunday into twin brothers and massively expanding Dano's presence in the movie, given how much larger Eli's role is.

And to say that Dano stands toe-to-toe with Day-Lewis - by no means an easy feat - is quite the understatement, so perfectly cast he is as the weaselly, insincere preacher who so ill-advisedly crosses Day-Lewis' oil man Daniel Plainview.

Dano should've received a Best Supporting Actor Oscar nomination for his performance, but all the same, it remains his finest work to date - impressive for a part he jumped into with effectively zero prep time.