I love just about all those already mentioned.  The Thing and The Shining could be the closest to perfection.  The Thing was incredible for how it created a sense of claustrophobia in a vast, remote Antarctic wasteland.

 

I'll add... Evil Dead I and II (original, though it's also dark comedy)

 

The Descent

 

Jeepers Creepers

 

Invasion of the Body Snatchers (78)

 

Halloween (original)

 

Nightmare on Elm (original)

 

Feast (it's part comedy too.)

 

Texas Chainsaw Massacre (original)

 

The Wicker Man (original)

 

The Exorcist

 

American Werewolf in London

 

Poltergeist

 

I like pretty much all Romero's "Dead" series, both old and new even though a couple of the last ones are only meh.

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