Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Nightmare Fuel: Doom House
The Face of Evil
That creepy voice that threatens Reginald on the phone. *((Shudders))*
Reginald destroys the doll that is harassing him and seeks comfort in his bed... only to find that same doll IN HIS BED WITH HIM!!!!
What's especially scary about this is that people generally think of their bed as one of the most comfortable and safest places one could ever be. When I first saw Reginald's sense of comfort and safety get violated by that doll, I was so disturbed that I was not able to sleep comfortably in my own bed for the next THREE MONTHS!
Reginald is calmly enjoying a video game, one of my favorite pastimes, and then he notices something happening that isn't a part of the game program. And he's not using a game corruptor!
When Reginald is clearly going mad from the doll's constant harassment.
"LEAVE MY HAPPY HOUSE! LEAVE!"
Before this moment in the story, mentioned above, there are even more signs of Reginald's building insanity that are just as haunting. Namely, when Reginald is driven to murder the doll in the garbage disposal and clearly finds pleasure in doing this and watches on with menacing glee!
That night shot where it shows SOMETHING quickly advancing on the house accompanied by a rather disquieting noise will always be with me whenever I'm alone at night. What WAS it? Oh man... who knows. It doesn't ever tell.
The doll constantly warps reality and people's perceptions of it. This is pretty a scary thought when you think about it.