The Slumber Party Massacre (1982)

  Man, Ted Bundy really scared the shit out of people.  This isn't specifically about him, but it definitely has Bundy overtones.

Trish (Michele Michaels) uses her parents' trip as an excuse to invite her friends over for a sleepover, unaware that a notorious serial killer has come back to town to continue his spree.  

That's it for plot!  This is very much a classic slasher with a lot of T&A, stupid horny teens, and gallons of fake blood.  Surprisingly, this was written and directed by women but don't expect any modern sensibilities about subverting the male gaze.  This is straight-up exploitation.  It was still more fun and a better watch than a lot of similar entries from the time, though.  Looking at you, Black Christmas.

The writer, Rita Mae Brown, is probably most famous for her series of cozy mysteries featuring Sneaky Pie, her crime-solving cat.  This is 100x more brutal than any of her books but does feature a lot of cats!  All of whom are useless at stopping the murderer, though.  

Slumber Party Massacre is currently streaming on Criterion as part of their 70s grindhouse horror feature from October so who knows how long it'll stay.  I think it's also on Shudder.