It may be too early to celebrate Christmas, but it's never too early for a Christmas slasher movie. IMDB:
A toy factory worker, mentally scarred as a child upon learning Santa Claus is not real, suffers a nervous breakdown after being belittled at work, and embarks on a Yuletide killing spree.
Utterly unnecessary remakes of "The Grinch" - eat your heart out.
Bonus trivia: "Christmas Evil" is John Waters' favorite psycho killer Santa movie. You may take that any way you wish :-) Also starring Fiona Apple's dad.