- "The problem with your daughter isn't her bed, it's her brain."
- ―Dr. Klein
Dr. Klein (Played by Barton Heyman) is a doctor in The Exorcist who is trying to help Regan and figure out what's wrong with her. Later at the McNeil's residents, Dr. Klein gets smacked in the face by Regan and is rushed to a hospital and is never seen throughout the rest of the film.
- The problem with your daughter isn't her bed, it's her brain.
- (Trying to give Regan a needle) This is to help you!
- (Referring to Regan) Her condition isn't quite what it seems, Ms. McNeil. Nobody knows what the cause of her hyperkinteic behavior is.
- Lesion in the temperal lobe. It's a kind of seizure disorder.
- (In a deleted scene after getting hit in the face) HELP ME! HELP ME!