One recent movie that gave me the chills was the sci-fi horror Pandorum (2009).
Had to watch it in the dark.

I guess that could freak out a new generation.

Poltergeist II was also very scary as a kid, especially the preacher.

Child's Play

Just the thought of something small and inocuous being in the house and killing you....

I've seen all the movies since my late teens and find nothing scary about them but as a kid....

The 1958 version of "The Fly". Specifically, the classic final scene of the tiny half human/half fly trapped in the spider's web pitifully crying out, "Help me...." as the spider approached.

I've had a fear of spiders ever since.

Stephen King's "Carrie". To creepy for words. Teleknesis, I almost believe. The psychology of this movie with the mother/daughter issues, religion issues and bullying. Kinda hits all the bases of being a teenage girl. Ok a really really disturbed teenage girl.

The original Frankenstein. What a classic! I was so scared I slept on the floor between my brothers beds.

Poltergeist...
I was about 7. Mum picked me up from school and on the way home we bumped into my auntie. We went to her house for a cup of tea and without being warned I walked into her front room, curtains shut, to be faced with my older cousins watching the ending of a pirate copy.
I was a bit shocked, but it wasn't so bad until a few weeks later when I was stuck on the sofa in front of the news ill with flu, mum and dad outside in the garden when the news reported this new film and showed the trailer, you know with the snowy screen, the little girl saying "They're here" and the hands on the screen.
Bricks were shat for a long time after that.

chucky hands down, my nana used to run a haunted hayride and she would watch horror movies to get ideas for it. so watching chucky at around 4 or 5 years old every stuffed animal of any sorts that i had was shoved into my closet and locked this included teddy rockspin, though i still that that little sob is as creepy as heck

Mine would have to be Amityville Horror

I remember being 4 and my brother who was 12 kept going on and on about how the story was "true" and so when I finally saw it, I believed it was real and I think it was the first time I was ever aware of evil as a concept. What made it even more terrifying was that evil wasn't just some abstract idea.......it was an entity! I really do not think I knew fear, real gripping emotional terror until I had this experience.

I watched Candyman when I was about 9-10, It got to me, it is very psychological and it scared he crap outta me.

Others that I remember watching young, ANOES. Maniac Cop. Friday the 13th. Halloween. None of these had the same effect as Candyman.

Oh I had to turn off "The Fly" with Jeff Goldblum, when he started taking his fingernails off, I almost quit it when he puked on the dohnut, but the Fingernails sealed it.

I have watched it amny times since, all the way through and it's still just as sickening.