Director: Roger Christian
On the surface, Battlefield Earth looks like just another Star Trek or Star Wars clone, but it's actually based on one of L. Ron Hubbard's most popular books and is part of the backbone of the Church of Scientology. The movie features many of the religon's teachings, with the most obvious one being Hubbard's views on psychiatrists. Hubbard had a strong distrust of anyone who could use their influence over another person’s mind. He believed that these psychiatrists could bend the will of people and control their thoughts, whether through hypnotic therapies or dangerous drugs.
It only makes sense, then, that the main race of villains in Battlefield Earth happen to be called Psychlos, with the main one, Terl, being infamously played by John Travolta. In the movie, these Psychlos have oppressed humanity and turned them into slaves, but they themselves are also ruled by a group known as the Catrists. The Catrists use mind control to impose their will on the Psychlos, as well as anyone else in their way, under the guise of being mental health experts.
Obviously this all builds on Hubbard’s feelings towards psychiatrists (Psychlos and Catrists even sound like psychiatrists when put together) and how he felt like they could destroy the will of a person, while claiming they are there to help.
Battlefield Earth is still the most highly-publicized Scientology film ever produced, and it's still the only way for the average person to get a glimpse at some of the religion's most cherished ideas. It's also hailed as one of the worst movies of all time by almost anyone who has seen it, so, you know, watch with caution.