Dylan Schnabel’s review published on Letterboxd:
Black Christmas is what happens when a director decides to make a slasher but also decides to make a good movie.
Each character has a purpose. By that, I don't mean simply to drive the plot along. Each character is a person, and they each have their own unique personalities and motivations. Barb isn't just the drunk and morally abrasive stereotype; she's driven by her jealousy and likely by issues from her childhood. Each character feels about as deep as her, at the least.
The only character who isn't fully explained is Billy, and that's for the best. Billy isn't a character we want explained, and it only drives the horror deeper that he isn't.
This should be on every horror fan's Christmas playlist.