10 Best Movies With An Unseen Enemy

5. Black Christmas (1974)

Black Christmas is one of the earliest entries into the slasher genre, an extremely influential film without which John Carpenter's Halloween likely wouldn't exist.

And while the genre is usually defined by a killer, whether masked or not, with a memorable look, name and identity, Black Christmas never gives audiences a clear look at the antagonist (Nick Mancuso) beyond his shadowy figure.

His name is implied to be Billy and we hear him make a number of obscene phone calls to the poor sorority girls he's stalking, but his face is obscured throughout the film and nothing approaching a concrete motive for his murderous antics is ever given.

Director Larry Clark suggested the idea of an anonymous killer himself, though screenwriter A. Roy Moore took some convincing before agreeing to it.

The result is an uncommonly chilling entry into a genre that didn't take long to become tired - even if the lack of a merchandisable protagonist arguably harmed the film's franchise potential.

As a one-off, though, it's creepy as hell and a sure-fire holiday classic.