Gremlins is definitely too scary for kids (the first one is a genuinely scary movie, the second one is a comedy). But it's also not quite a "kids movie" even though it was originally rated PG.
Labyrinth and Neverending Story are scary, but not too scary. What I mean is, they scared me and it stuck with me, but that's not a bad thing. It's good for kids to have a healthy fear of wolves. To this day I know not to search out and explore wolf caves.