A Christmas Treat (4:17)
Halloween Short Films; IMDb; YouTube

This came out in 1985, but I first saw it in 2018, while checking out a list on iHorror (from 2013). A young boy's parents put him to bed on Christmas Eve, warning him not to try to sneak a peek at Santa Claus. Of course he ends up disobeying, and of course that ends up being a very bad idea. But what's really horrifying is... well, I won't spoil it. So, I don't know what else to say, except that I suspect this short may have inspired other filmmakers' own holiday horror films (short or otherwise). It really is sort of amateur, but that only adds to its charm. Or whatever.