Fresh off the success of Iron Man, Robert Downey Jr. is in talks to star in Universal's Cowboys & Aliens according to The Hollywood Reporter. The film, which has been in development over the past 10 years, is a mix of sci-fi and the Western genre and it could hit theatres in 2010 if everything comes together. Downey Jr. will next appear alongside Ben Stiller and Jack Black in Tropic Thunder, which opens August 15th.