Edgar Allan Poe/Nightmare Fuel

Most of Edgar Allan Poe's fiction is too nondescript to really qualify for Nightmare Fuel, but when he wrote scary, he did it well.

The Black Cat
""Gentlemen, I delight to have allayed your suspicions. These walls -- are you going, gentlemen? -- these walls are solidly put together.""
 * The decaying mental health of the protagonist, and the way he treats the poor cats, is very unsettling.

Berenice

 * She was alive and conscious while he was messily yanking out her teeth. Ick. (And she was not alive after, which might just have been her finally dying from the illness they thought killed her before, but...) It's worth noting that even Poe thought he'd gone a little far into gruesomeness for gruesomeness's sake with this story.
 * The narrator's obsessive personality disorder can be quite the source of Paranoia Fuel if you start noticing similar tendencies in yourself.

The Cask of Amontillado

 * Dude, Fortunato gets sealed up alive behind a wall of bricks!
 * What's even worse is that we don't even know why Fortunato is sealed away. What exactly did he do to get that sort of reaction?
 * In animated adaptation, the moment when.

The Facts in the Case of M. Valdemar
"I have been sleeping... and now... now..."
 * The whole concept of this little-known tale is terrifying. A man hypnotized on the brink of death is frozen there for weeks, and when he's brought out of the trance, . This story must have been doubly unsettling to the people who thought it was a real scientific report back when it was originally published.
 * Harry Clarke's illustration of the finale is so well-executed you can almost smell it.

The Fall of the House of Usher

 * A person's first reading of this is sure-fire sleep deprivation.

The Masque Of The Red Death
""And now was acknowledged the presence of the Red Death. He had come like a thief in the night. And one by one dropped the revellers in the blood-bedewed halls of their reve, and died each in the despairing posture of his fall. And the life of the ebony clock went out with that of the last of the gay. And the flames of the tripods expired. And Darkness and Decay and the Red Death held illimitable dominion over all.""
 * The description of the disease, and the ending.

The Murders in the Rue Morgue

 * Historical note: The first detective story, ever. The murderer's identity kind of ruins it as murder mystery, but ramps up the scare factor.

The Pit and the Pendulum

 * The whole chamber is horrifying, especially the thought of being crushed by two, moving walls.
 * Helplessly watching your death tick closer and closer... tick tock, swish swoosh.

The Premature Burial

 * The prospect of being buried alive is Nightmare Fuel, no matter how you slice it.

The Raven

 * Both James Earl Jones' and Christopher Walken's readings are very chilling.

The Tell-Tale Heart

 * How in the world could someone be so calm for killing someone, then chopping their limbs off and stuffing them under floorboards? Not even that, but SITTING on them!
 * A dangerous madman, who else?
 * "The Tell-Tale Heart", while creepy, doesn't fall into this when you just read it. But that dramatic monologue, acted aloud in a theatre, increasingly hysterical and seesawing between cool description and feverish mania, with the last line either screamed or sobbed -- yeah.
 * You think that's creepy? Try the audiobook version. Following the scene where the narrator does his thing, they start playing a sound every second or so. At first you think you're hearing things, until the point where it gets loud enough to know that you're listening to a heartbeat.

William Wilson

 * William Wilson runs into all kinds of trouble because of his drinking and partying.