Tropic Thunder (2008)

 This comedy/action romp charts the filming of a guerrilla-style Vietnam War movie that derails thanks to the egotistical actors, including Kirk Lazarus (a blacked-up Robert Downey Jnr). Even with its all-star cast (Nick Nolte, Steve Coogan, Ben Stiller and Jack Black among them), the standout performance is by Tom Cruise as megalomaniac film producer Les Grossman.