Great thread! A movie that comes to my mind is Vincent Price's Masque of the Red Death. I was in my 40's in a hotel while on business travel, and this movie came on. I had ignored it in the past but decided to watch it and got TOTALLY creeped out! It was creepy but also disturbing, and I wished I had not watched it by myself in an unfamiliar place. I had serious trouble sleeping that night

a movie called "Seconds" (1966)
so many movies, so little time

The exceptionally well crafted and sustained spooky ooga-booga gloom-doom atmosphere is what makes this film one of the great atmospheric horror gems from the early 1960's. Messiah of Evil also has a similarly creepy and disquieting mood to it.
I've been chasing grace/ But grace ain't easy to find

For the sense of isolation, I'd recommend any Antonioni film.

I strongly recommend Messiah of Evil for the same sense of isolation, creepiness and surreality. I think CoS is the better film, but Messiah does have a similar feel.

No one mentiions about
REPULSION
?! Watch it right now!
There's something wrong with Esther.

Deathdream directed by Bob Clark is also creepy. It has a terrific ending.

To me "The House of Seven Corpses" has a similair creepiness! It is very different movie and is not really a very well writtened film, but its creepiness of Seven Corpses was alway fun to watch, especially the introduction! So was many of the other low-budget schockley horror films of the 70's!

Suspira.

Good call on Mark Of The Vampire! I understand the connection right away and know what you mean. One of my favorite sequences is the person playing the organ while the female vampire floats down. Very effective!

An outstanding, and much sought after for many years, little horror film just finally came to DVD called
Don't Be Afraid of the Dark
.
It was originally a TV movie that came on back in 1973 and after watching it for the first time in decades the other night I can tell you first hand that it's still crazy creepy!
Low budget, moody, atmospheric and nightmarish.
You should also check out
The Changeling
with George C. Scott, one of the all time great ghost stories.
If you expect the unexpected doesn't the unexpected then become the expected?

It's hard to match this film but I would mention Suspiria, The Shining and maybe Session 9. Someone mentioned City of the Dead which is creepy too but not as creepy as COS.
The Planet of the Vampires is also worth mentioning.

The Orphange.
It's a spanish film but the last 15 min's are creepy and moving.
Elvira mistress of the dark is the coolest woman ever.
"Revenge is better than Christmas"

I agree. It was really creepy. I liked it. Especially in B & W. It was a nice departure from today's CGI-driven horror. The carnival and pier was really disturbing. Great low-budget scares!
Another old movie you might want to try with a similiar eerieness is "The Innocents" with Deborah Kerr.

City of the Dead, with Christopher Lee.

I love
C O S
; it's delightfully creepy. There are lots of other great creepy films mentioned on this thread. One not yet mentioned that I find very creepy in a similar way is
The Innocents
. Gave me gooseflesh
I can resist anything but temptation.

Session 9.

Wow what a great board. nikhil gave some great recommendations.
I'd like to add Eyes Without a Face to the list.

"I Walked With a Zombie" isn't as creepy as this one, but it's pretty creepy nonetheless. I know it has one of the worst titles ever, but it's one of the best movies.

Meshes is a great example.
Picnic at Hanging Rock, Last Year at Marienbad and Persona also have a similar ethereal mood.

I just watched CARNIVAL for the first time last night. The ghoul makeup was really simple, but for some reason those faces coming out of the water scared the silly out of me. My six year old who has watched Harry Potter and isn't bothered by the dementors or other creepy characters was freaked out by the white faced man.
THE HAUNTING (1963) was very atmospheric and creepy. It is amazing how terrifying the scene is where there is something coming down the hall and there is this banging, no special effects, just suspense. The remake was horrible.
Also, SOMETHING WICKED THIS WAY COMES (1983) is another fun movie. I watch both of these every Halloween. I may add CARNIVAL to my list.

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John Carpenter's "Prince of Darkness" is a bit of a cheesy film but has an overall creepy feel to it - check out the dream sequences.

Let's Scare Jessica to Death. The stories are not similar at all, but it has the same kind of uneasy creepiness throughout.