Black Christmas

Four years before Halloween, and still the most frightening film in the category.

A sorority house before the Christmas break, obscene phone calls, and somebody already in the attic.

Bob Clark, who later made Porky's and A Christmas Story, establishes almost every slasher convention here: the killer's point of view, the holiday setting, the calls coming from inside, and a final girl. Carpenter has acknowledged the debt directly.

What separates it is that the killer is never explained, never named, never shown, and never caught. Billy is a voice and a shape in an attic, and the phone calls, performed by several people layered together, are disturbing rather than atmospheric.

Margot Kidder is very funny in it, which nothing since has bothered to try.

The last shot is a house with a phone ringing in it. That is the whole ending.