* CompleteMonster: The Stranger is a SerialKiller who stalks, terrifies and eventually murders young women just for the joy of it. He prefers to target babysitters, having no compunction about killing the children they’re watching over either. He kills a random babysitter and two kids on the other side of town, then preys on Jill for the rest of the film, killing her best friend Tiffany in the proces. He's eventually stopped and arrested, but the trauma from the experience is so great that Jill suffers a psychotic break, dreaming that the Stranger is still there to torment her.
* ItWasHisSled: The fact that TheCallsAreComingFromInsideTheHouse was originally a shocking twist. The [[TrailersAlwaysSpoil trailer for the remake]] completely spoils this, as well.
* OlderThanTheyThink: The "TheCallsAreComingFromInsideTheHouse" trope was not invented by this movie, but ''Film/BlackChristmas1974''.
** And it was an urban legend before that, too.
* ParanoiaFuel: These films basically play on the fear of a) being alone in someone else's house, and b) unusual noises inside said house.