Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Nightmare Fuel: Sin City
Though several aspects of the series of the film are just terrifying, the mere fact that Kevin not only ate part of Lucille,but made her watch him suck the meat off the fingers of her severed hand takes the horror Up to Eleven.
"He made me WAAAAAAAAAAAAAAATCH"
Before he eats a girl, he locks her in a room decorated with severed heads of the girls he's eaten. All so the girl would become extremely terrified of her fate.
His eyes, his goddamn eyes. They stare straight into your soul.
Marv: This is a bad place, this farm. People have died here. The wrong way.
Hartigan: You're not a rookie for a week before some dead-eyed veteran gives you the word. Don't ask about the farm at North Cross and Lennox. Don't even think about it. Go there, and you cease to exist. There won't even be a corpse. It's a place where very bad things have been going on for a very long time. Generations. Junior came by his proclivities honestly.
"Recognize my voice, Hartigan? Recognize my voice, you piece-of-shit cop? I look different, but I bet you can recognize my voice!" That Yellow Bastard indeed. The book is pretty nasty with him showing his face again, but the movie and Nick Stahl's acting just makes it even more creepier.
Even worse afterwards. Junior reveals that he was not in a coma for those eight years (though he may have been for some) and has been raping and murdering little girls the whole time.
"They all scream Harritan. Dozens of them, maybe hundreds. Eight years worth of girls."