I'll go first:

http://www.youtube.com/watch?v=EWAVI4x3bIo

This.

Hellraiser. The whole movie.

Cant post a clip.

I walked in on my older brother watching a porno when i was about 5. I thought it was a wierd murder scene for a second and then just got confused.

http://www.youtube.com/watch?v=tjEdLuqK1RQ

I can't post a clip as basically it was the entirety of "A Nightmare on Elm St". I could NOT sleep that night, I kept hearing "One, two Freddy's coming for you" echoing in my head :(

this
i saw that movie in the theater when i was five, and that face just scared the crap out of me.

Couldn't find a clip immediately, but the Wrath of Kahn's mind control bug thing always freaked me out. I need to watch that again.

I don't think my childhood was ever "scarred". I'm pretty sure I was born desensitized. There might have been a minor issue with the first live-action TMNT movie (seeing the "boys" almost die "In Real Life" as opposed to in a cartoon), but that cleared up pretty quickly by the time "Secret of the Ooze" came out.

http://www.youtube.com/watch?v=o-4f_NMUxcY

Nightmares for months.

Spiderwalk.

showing my age here. This came out when I was 5. It doesn't seem scary at all now, but if you read the comments you'll see a lot of people talking about how it terrified them when they were little kids. It was actually pulled because of the complaints from parents. I couldn' t even look at the tv when this came on. Nothing terrified me more (besides The Exorcist)

http://www.youtube.com/watch?v=Lx7smh7YHKg

The Thing

Link

I was older (10) so it didn't terrify me as much, but anyway:

http://www.youtube.com/watch?v=yc7oJhvNr4w