The popular consensus is that Alfred Hitchcock's Psycho kicked off the slasher movie genre, and that's a fair assessment. But, if you break it down, Psycho only has two on-screen killings, which doesn't exactly qualify it as a fore-bearer to the likes of Halloween and Friday the 13th. The unsung first of that multiple casualty slasher is, in fact, Bob Clark's severely underrated gem Black Christmas, about a killer hiding in a sorority house's attic and systematically slicing through the pretty sisters.
And like the best of slashers, Black Christmas has a formidable, not to mention beautiful, "final girl," Jess Bradford (played by the stunning Olivia Hussey). Before the bodies start piling up, Jess is already stressed out. She's on the verge of having an abortion, even though her boyfriend (Keir Dullea) isn't happy with the decision. So the last thing she wants to deal with is a homicidal loon skewering her girlfriends.
Still, in light of having one truly shitty semester, Jess proves to be the only sorority sister who's able to overpower the killer, whose identity won't be divulged here. The excellent Black Christmas deserves all the curious viewership it can get.