Billy

First appearance: Silent Night, Deadly Night (1984)

A young boy has a bad experience with a Santa Claus and ends up in an orphanage with a severe case of Santaphobia.
When he's older he gets a job at a tryster. when Christmas rolls around and the man who was supposed to play Santa calls in sick it's up to Billy to take over. Now every naughty boy and girl get's to have a bad experience with a Santa Claus!

What's with Christmas horror movies having a main character named Billy?

Vance

First appearance: Digging Up the Marrow (2014)

The Director of Hatchet makes a documentary about monsters after being approached by a man who not only claims monsters are real but that he knows where to find them. Is this man crazy or do monsters actually walk among us?

Doom-head

First appearance: 31 (2016)

Some carnival folk run afoul of some weirdos who like to dress up in powdered wigs and sic killer clowns on people at an abandoned power plant on Halloween! Who will survive the terrifying halloween game 31? what will they win if they survive?

Billy

First appearance: Black Christmas (1974)

Something not nice is happening at a small sorority house near the campus of a Canadian college just before Christmas holidays ...

 One of the first major Slasher movies and the inspiration for the film Halloween!