When i was a kid, i was traumatized by Fly (1986), Terminator 2's T1000, Robocop 2's Kane monster, and Ernest scared stupid. I watched old horror movies (Frankenstein, Brain that wouldn't die etc...) with my dad and sneaked into my school-pal's place to watch Bad Taste when i was six years old. Back then those movies really freaked me out, but were somehow better than any other films. And the movie Sirius 6B was fucking terrifying, because of the beginning of the film. This soldier gets he's arm and leg chopped of by a robot.
But now, i have them all on DVD and they're still better than most movies i've seen.
I have mention two more things that REALLY freaked me out: Birth giving nightmare of the Fly and Highlander's head chopping moment.
No, these aren't any kids movies, but movies i watched when i was a kid.