The Entity (1982)

Single mother Carla Moran is raped and attacked by an invisible force. She begins therapy with Dr. Phil Sneiderman, a psychiatrist who believes Carla's traumatic past is motivating her to commit self-induced injuries, rather than anything supernatural. When the attacks continue, Carla invites two college students with an interest in the paranormal to visit her house. After seeing the ghost in action, they agree to help Carla defeat her invisible attacker.