What scares you the most in horror films?

[Vik]

For me it's probably ghosts, even if I lack a belief in their existence (because I often hear people answer serial killers, seeing they exist). For the reason that I wouldn't have a clue what to do if I actually saw a ghost, and I'm unsure how you'd defend yourself against one. Serial killers, vampires, zombies etc. can all be killed. Not so sure about ghosts.

[Mofo Rising]

I don't get scared by the obviously supernatural. In fact, I rarely get scared at all by any movie. Wish I could, some of my fondest memories are being absolutely terrified as a child. I would love to be able to get back to that place, but that's not in the cards.

I do like the unknown and the eerie. The best example I have seen recently was the movie "The Mothman Prophecies." The Richard Gere character finds himself in a strange web of synchronicity which can not be easily explained. He's offered the choice to drag himself into it, but holds off. But the voice on the phone accurately predicts the future. That was the best example I've seen of the supernatural intruding on real life. Fantastic stuff.

But do you know what really scares me? The fragility of human life. Gets me every time. I remember watching Saving Private Ryan in the theater. Storming the beach at Normandy was one of the greatest things I've ever seen put to film, but it didn't bother me. What did bother me was one scene at the end where one of the soldiers attempts to put a "sticky bomb" on a tank. He doesn't get the timing right, and when the bomb explodes he is liquified. That scene crawled up inside my soul and died. Fragility.

[Vik]

I don't get scared by the obviously supernatural. In fact, I rarely get scared at all by any movie. Wish I could, some of my fondest memories are being absolutely terrified as a child. I would love to be able to get back to that place, but that's not in the cards.

Yeah, same here. But if I am it's usually ghost-stuff. Although watching some internet videos with supposed ghost sightings probably has a lot to do with it.
( http://www.xenvideo.com/2006/11/25/hitchhiker-ghost-causes-car-accident/ )

[Jack]

It's kind of ironic with all the supernatural beasties and gigantic monsters about, but the thing that "scares" me the most would be plain old human beings and the cruelty they can inflict on each other.  The remake of The Texas Chainsaw Massacre with Jessica Biels was the only movie in many years that really stressed me out.  R. Lee Ermey far more than Leatherface.  The way he could just casually scare the livin' s*** out of the characters, they might die at any second because he just wouldn't have thought anything at all of doing them in.  And I guess it's closer to our real-life experiences as well, so it has a bigger effect on us.

[Trevor]

Any thing hiding in the dark and hiding his / her face ~ there is a scene like this in The Crimson Rivers. 

[bob]

ungodly amounts of blood make me feel somewhat nauseous

[Kaseykockroach]

I hate jump scares. Always have, pathetic as it sounds. No matter how much I see them coming, they still work on me. I just hate being startled, even just a little. -groans-

[JaseSF]

The Japanese pale ghost kids get to me every time...seriously creep me out.

I actually find the Wendigo, which I consider a sort of werewolf/shapeshifter, terrifying as I believe I encountered one in my youth.

[Silverlady]

What scares me the most are the things "you can't see".  What's making the shadows on the wall or what is it "pounding" on the closed door?  Is it the wind howling or is it something else?  Did I see a shadowy figure at the end of the dark hallway? A sudden scent of roses filling a room? Something brushed my shoulder.
The hot coffee that is now suddenly ice cold. 

[retrorussell]

Gouged eyeballs have done it for me for many, many years.. much less so recently but if I dream about it I do wake up a bit sweaty.  Or ocular trauma of any kind I guess.

[Leah]

ungodly amounts of blood make me feel somewhat nauseous

Then I guess you wouldn't like Dead Alive? 

what scares me is parasites and the feeling that someone suffering through it.

[Mofo Rising]

ungodly amounts of blood make me feel somewhat nauseous

Then I guess you wouldn't like Dead Alive? 

what scares me is parasites and the feeling that someone suffering through it.

Seen The Ruins? Not the greatest movie, in my book, but it should push your queasy buttons.

[akiratubo]

Everyday things becoming terrifying.  (The friendly dog turning into a monster in The Thing.  The most frightening thing I've ever seen in a movie.)

Safe places becoming unsafe.  (That few minutes of The Strangers when the killers are trying to get in while Liv Tyler is home alone.)

Losing control of your body.  (The 1986 version of The Fly ... Bartok's fate in The Fly II even moreso.)

Nowhere to run, nowhere to hide, no way to fight back.  (The feeding frenzy in Piranha 3D.)

I'm not sure how you'd classify it but the original Terminator scares the hell out of me.  Partially, it's because he's implacable and unrelenting, but I think it's mostly because he's really good at what he does.  Sent into an unfamiliar time and place, with no resources and nothing to go on but a name, the terminator tracks down his target within a few hours.  The best the hero can come up with is to keep running and hiding for a few hours at a time before the terminator finds them again.  Even when reduced to nothing but an arm and a torso, the terminator still keeps coming and almost succeeds.  He was a truly unstoppable threat who completely outmatched the heroes.  (Contrast this to the mostly ineffective T1000 and the completely worthless TX from the later movies.)

[bob]

ungodly amounts of blood make me feel somewhat nauseous

Then I guess you wouldn't like Dead Alive? 

what scares me is parasites and the feeling that someone suffering through it.

Seen The Ruins? Not the greatest movie, in my book, but it should push your queasy buttons.

I saw Dead Alive once. I lost my appatite watching it and was a bit hungry before starting it. Never seen The Ruins.

[RCMerchant]

What scares me the most are the things "you can't see".  What's making the shadows on the wall or what is it "pounding" on the closed door?  Is it the wind howling or is it something else?  Did I see a shadowy figure at the end of the dark hallway? A sudden scent of roses filling a room? Something brushed my shoulder.
The hot coffee that is now suddenly ice cold.  

Well said,dear!
Tis may sound goofy,but the cheezy classic the BRAIN THAT WOULDNT DIE scared the hell outta me! The thing in the closet...and the build up to it busting down the door...me and my brothers were watching it on Shock Theater...when the monster finally broke out-my step brother Jimmy screamed and hid behind the couch! Now THATS entertainment!

http://www.youtube.com/watch?v=ddjSIP6bhCI&feature=related

A classic example is the pool scene in the CAT PEOPLE...
dammit! Click on the "Watch on You Tube"...it wont let me embed it...morons!

http://www.youtube.com/watch?v=zfbGJrAVWUo