Personally, the scariest movie I've ever seen is "Forrest
Gump." That's not because of anything in the story, but because of the way that Robert Zemeckis was able to splice the images of Tom Hanks into all that old film footage. Imagine if some unscrupulous film editor was able to get film footage of, say, some gruesome crime in progress and splice your picture into it.

Watership Down
thats meant to be a kids movie.
its a sure fire way to mess them up for life o.O