Bughuul

First appearance: Sinister (2012)

A heart warming tale of a true crime author discovering a box full of home movies in the attic of the house he just moved into. Wait, did I say heart warming? I meant terrifying.
The plot follows the crime writer's attempt to unravel the mystery of a family who is hanged in their backyard and their missing daughter. The murderer conveniently leaves the author clues as to what happened in the form of a box full of deceptively labeled snuff films in the attic of the house where the murder took place and the author has just moved his own family into.
Very creepy movie involving pagan gods, horrible murders and a guy who just wants to write a book about the murders.

That guy giving out tickets...

First appearance: Demons (1985)

Some creepy dude with a metal mask melted into his face hands out tickets to a free screening at a movie theater that's been closed for many years. The people who end up going to the show find out that either the movie or the theater is cursed when a prostitute who was out on the town with her pimp scratches her face while trying on a silvery devil mask that's part of a display in the lobby of the theater and turns in to a demon, just like in the movie they're watching! Mayhem ensues.
Lesson learned? Don't go to movies at closed theaters advertised by mute disfigured freaks.
Features the greatest example of a Deus Ex Machina in a movie that I can think of.