OOh, nice topic. I think there should be more Christmas Horror movies lol. I can'tt hink of any that weren't mentioned. I know there's a new one coming out in theatres soon called Black Christmas.
Here's a link with some movies. I remember this one,
Silent Night, Deadly Night(apparantly there's a bunch of sequels, I meant the first one lol). That one scared me when I was a kid.
http://www.hollywoodinvestigator.com/christmashorror.htm
Check out for...
A Christmas Story (Ralphie) 1983.. not a horror movie...but worth watching.
National Lampoon's Christmas Vacation...
How The Grinch Stole Christmas 2000..