The test of a truly great horror movie is whether it can still scare the pants off of viewers even after repeated viewings. CG monsters may come and go, but the shark from "Jaws" and the shower scene from "Psycho" will live in our nightmares forever.

As we get into the Halloween spirit, we're looking back at 10 iconic horror moments that have stood the test of time. No matter how many times we watch these films, these moments always fill us with dread.

1. The Chest Burster Scene From 'Alien' (1979)
Poor Kane. Just when this plucky space trucker thought he had emerged from a close encounter with a Facehugger none the worse for wear, he found himself being devoured from the inside out. The fact that the actors weren't expecting the Chestburster any more than the viewers really made this scene that much more visceral.

2. "You're Going to Need a Bigger Boat" From 'Jaws' (1975)
For the first two thirds of "Jaws," the shark was mostly an unseen menace threatening the citizens of Amity. But this leviathan made its debut in a big way as it emerged from the depths and left poor Chief Brody shocked and stupefied.

3. Locked In the Closet From 'The Sixth Sense' (1999)
"The Sixth Sense" has plenty of scary moments, but none stuck with us more than the scene where Cole was locked in a small space with a very angry ghost. His screams of terror and pain were worse than anything the movie could have actually shown us.

4. The Elevator of Blood From 'The Shining' (1980)
"That's odd. The blood usually gets off on the third floor." Elevators are creepy enough for anyone who suffers from claustrophobia. But when you have elevators that act of their own accord, and spew rivers of the red stuff... well, we're not eager to visit any remote mountain hotels any time soon.

5. The Chest Attack From 'The Thing' (1982)
It's tough to think of a Hollywood monster more inhumanly terrifying than the titular creature from "The Thing." This scene started off with a good jump scare and then showcased the creature undergoing a grotesque, horrifying transformation even as it was torched to death by the ever vigilant MacReady. There's no way we'd be able to maintain our composure in that situation.

6. Ben Gardner's Boat From 'Jaws' (1975)
Can't fault us for having two scenes from "Jaws." This second jump-scare is a perfect example of why less is often more when it comes to horror. The tension of seeing Hooper dive into the water when a giant, man-eating shark could be anywhere in the area was bad enough. The shock of seeing the bloated corpse of Ben Gardner rear its head is enough to haunt our dreams even still.

7. The Head Spin From 'The Exorcist' (1973)
This scene is one of the main reasons why "The Exorcist" is still regarded as one of the scariest movies ever made. The sight of young Regan's head pulling a 360 isn't even as bad as the sound of her neck straining and cracking.

8. The Blood Geyser From 'Nightmare on Elm Street' (1984)
Johnny Depp's first claim to Hollywood fame was suffering through this incredibly gruesome death scene. The result was a geyser of blood big enough to make even the ghosts of the Overlook Hotel jealous.

9. Sloth Wakes Up From 'Seven' (1995)
It's clear from one look at the disturbingly emaciated body in this scene that John Doe's latest victim is dead. Which, of coruse, makes it all the more shocking when he wakes up and gasps for air.

As with "Alien," the fact that even the actors didn't know the body wasn't just a dummy really added to the impact.

10. The Shower Scene From 'Psycho' (1965)
Is there any place people feel more vulnerable than in the shower? "Psycho" certainly didn't help, as this dramatic murder (punctuated by some truly creepy string music) quickly became one of the most iconic horror scenes in Hollywood history.