Simon

A 1980 American comedy film starring Alan Arkin as Simon Mendelssohn, a psychology professor manipulated into believing he's an alien from space by a think tank, who use his ramblings to create a media circus and later try to kill him after he becomes too famous. As Simon goes on the run with his girlfriend Lisa, he's forced to confront the reality of his identity and eventually comes to accept that he's human. Along the way, they encounter a bizarre commune that worships television and outlandish schemes from the think tank, led by Alan Arkin in one of his most memorable roles.