As an autograph collector for quite a few years now, I really don't think they would go through the trouble of forwarding the letter to the celebrity.

I was wondering if sending to the production company was a good idea. I want to write to some of the stars of a film called Knights of Badassdom and the only address I can find is that of Indievest Pictures, the film's production company. Do you think it's worth a shot sending to that c/o the film.