This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Nosferatu
He is coming...
From the 1922 film
For something nearly a hundred years old, this film has aged surprisingly well, especially in regards to Max Schreck's performance as Count Orlok.
A famous scene: Hutter opens his chamber door and sees Orlok standing, dead eyed at the other end of the hall. He closes the door in fear, and finding no way to bar it, cowers in his bed. The door opens seemingly of its own accord, before Orlok emerges from the darkness, and stiffly walks into the room.
The scene where Orlok is peering from behind the window of his house. It still has a scary feel to it and inspired countless similar scenes in horror films ever since.
The crawling shadow of Nosferatu has been done many times, but still remains creepy.
The massacre of the ship, where Orlock slowly destroys each crew member before sliding into the port.
From the 1979 remake
In Werner Herzog's 1979 remake the opening shots are rather creepy. We first see images of real preserved bodies filmed inside the catacombs of a Mexican graveyard. Then a slow motion shot of a flying bat in black-and-white is shown. This is followed by actress Isabelle Adjani awakening from a nightmare and screaming out in fright.
The scene in the remake where Harker meets Dracula. He prepares a meal for him and while Harker eats Dracula never takes his eyes off him or even blinks. After a few minutes Harker cuts his finger and Dracula tries to suck the blood from it. When Harker pulls away they stare at each other for a moment before Dracula knocks Harker's chair aside and moves toward him. Harker backs away into a chair in front of the hearth and Dracula visibly struggles to restrain himself.
From the SNES video game
The game over screen can be this once you realize that the photograph slightly alters itself to reflect Erin's vampirification.