Do actors have to auddition for movie roles?

It all depends on the situation. Seth Rogen wrote Superbad. He was a big part of it's development. He didn't have to audition for the Cop role. It was "his movie". Or like when Ben Stiller writes, directs and produces a movie. It's his movie. He doesn't have to audition to be in it. Most of the time, actors do have to audition. Let's say you're a director and you want Jim Carrey to play the lead. You would hire a Casting Director. The Casting Director would contact Carrey's Agent. Carrey's agent would then talk to Jim about the role (and give him a copy of the script). If Carrey wants it, he goes in and does a "reading" with the director to make sure the director really does want him for the role. Now, to be honest, Carrey's probably a big enough star by now that he doesn't have to go through the regular process. But to answer your question simply....yes. MOST of the time actors have to audition for the roles they want.