Director: Bob Clark
Stars: Olivia Hussey, Margot Kidder, Keir Dullea, John Saxon, Marian Waldman, Andrea Martin, Art Hindle

If the concept of a killer making threatening phone calls sounds familiar, you're probably thinking of Mr. Ghost Face's preferred method of pre-slaughter intimidation in Wes Craven's Scream. Considering how in-the-know that film is when it comes to horror trivia, it's logical to think that Scream screenwriter Kevin Williamson was quietly paying homage to Bob Clark and Black Christmas.

He wouldn't be the only one, either. Give Black Christmas a look and you'll be taken aback by just how many of its ingredients have been pilfered by subsequent horror directors and screenwriters. In addition to the killer making phone calls, there's the third-act realization that "the calls are coming from inside the house," a dread-heavy reveal that, five years later, would be front-and-center in When a Stranger Calls. Playing the wisecracking, sassy best friend "Barb," co-star Margot Kidder provides inspiration for the countless scene-stealing slasher movie BFFs to follow, like, say, Rose McGowan's "Tatum" in Scream.

There's more. The film opens with a first-person POV shot of the killer scaling the house and entering, before killing his first sorority girl, and it's quite similar to the first-person POV opening of John Carpenter's Halloween, which came four years after Black Christmas. And, for good measure, it's worth pointing out that the old cop-stationed-outside-for-protection-gets-killed storytelling component used in Black Christmas has been redone to death, too. An example? Scream 4. Yeah, Kevin Williamson is a fan of Bob Clark's film.

As he should be. It'd be grossly negligent to write a self-aware slasher movie like Scream and not pay respect to Bob Clark's O.G. film, even if Black Christmas has never received the accolades and reverential acknowledgements it deserves.