Both fun old movies. The Black Christmas is really considered to be the First Modern Slasher. It kind of sets up all the Tropes everyone else used, and it was 5 years BEFORE Halloween... And it has Margot Kidder back when she was young! Hubba Hubba.
And SN/DN kind of Flipped the Slasher Trope where you follow the Killer more then the Victims. Came out the same year as NOES and was Actually doing Better then Freddy...until those uptight Parents Groups got it taken out of Theaters cause "We dont' want widdle kids thinking Santa is a Killer".
Cause ya know....Parents Groups can get really stupid...when a camera is on them...