Okay, I’ve mentioned this one twice already. I’d be remiss if I didn’t include it. My only reservation is that I haven’t been able to track a copy down to watch it again, and it has been a few years. But whatever. I will soldier on.
After his usually-catatonic grandfather gives him an prophetic earful about how Santa is a bad man, Billy watches his dad get killed and his mother get raped (and then killed) by a man in a Santa suit. This, of course, messes up his mojo and sets the course for him to don a Santa suit as an adult and go on a murderous rampage. Billy’s out to punish the naughty, as any good man ought to do.
See the movie Leonard Maltin called a “useless splatter film”!