The Exorcist 3
William Peter Blatty got an opportunity to make up for the disappointment that was The Exorcist Part 2 (episode here) with this installment, based on his novel "Legion" - this time, behind the director's chair. It's weird an uneven and (as usual) plagued by studio interference. But it IS the source to one of the single-most-notoriously-effective jump scares in horror cinema. And yes, we talked about that too.
Mad thanks to Adam for the request!