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Nightmare Fuel: Home Alone
The wreath of the McCallister residence at the beginning of the movie features a rather mean looking Santa, with his eyes in shadow Fist of the North Star style... and then they zoom in on the thing! Yeesh!
The furnaces "HELLOOO KEVIIIN!!" Doubles as in-universe Nightmare Fuel for Kevin.
Nullified by the fact that Kevin simply tells it to shut up, and it works.
Buzz's pet tarantula, Harry and Marv to some people, and a few of the booby traps.
Highlights of the booby traps: the nail through Marv's foot, the tarantula, the glass ornament stepping, the scenes with the furnace, and the electric sink. That wasn't Kevin down there in that scene...that was Henry Evans!
When Harry and Marv manage to catch Kevin, they gleefully claim that everything Kevin did to them, they're going to do to him. All those booby traps? Not so funny when you picture those things being done to an eight-year-old boy. Harry even said he was going to bite off all of Kevin's fingers, and had every intention of going through with it. He actually had one in his mouth before a shovel-wielding Marley came in to rescue Kevin.
Near the end, when Harry and Marv are standing over Kevin, paint all over them looking like dried blood, crazy slasher smiles...and the line "My, how the tables have turned". Brrrr.
Harry comes very close to shooting Kevin in Central Park. While the gun did turn out to be jammed, it's still a very unsettling scene of Harry wanting to savor killing a kid. On top of that, the way the gun sort of oozes when he takes it out of his coat isn't exactly a pleasing image.
The Oh, Crap moment when the now Sticky Bandits sees Kevin again. When Harry greets Kevin with a very Faux Affably Evil "Hiya paaaal!", Kevin turns around and to see the two towering over him with giant Slasher Smiles.
And when he rises his hand towards Kevin, revealing the burn in the shape of the doorknob in the first movie.
Keep in mind that based on some of the comments they made, Harry and Marv intended to kill Kevin right from the moment they saw him in front of the toy store - and that they probably had something more grisly in mind than just shooting him.
The Pigeon Lady standing and watching as her pigeons swarm Marv and Harry, especially when she laughs.
Marv getting electrocuted and turning into Skeleton-Marv for a few seconds was enough to scare the crap out of you.
Especially because Marv literally turns into a screaming skeleton for a few seconds.
The Cab Driver in the second film. Especially that creepy shadowed face of his. Double points for showing his face directly into the camera.