Jurassic Park for sure - I went to the cinema shortly before I turned 12 and I remember it well because it was a date with a girl who lived down the road. Fantastic movie. I saw it a few months ago with some nephews and nieces and it still holds up well, one of those films that will always be a hit with everyone in the family on a sunday afternoon.
Then the obvious ones, I honestly don't remember how old I was when I first saw Star Wars, Star Trek, Jones etc. but I was watching them alot around this time. I think I was about this age when I saw Aliens for the first time. One of those negotiations with my mother, which in retrospect helped enormously overcome my fear of aliens which I'd already seen outside of the context of the movies, firstly because my elder brother had a big poster on the inside of his room door (for years I was afraid to walk past it, which was difficult because our rooms were next to each other) and second because I was reading the comic adaptation of the movie.
Oddly though, I definitely saw Predator at this age and that hadn't been an issue. I did get in trouble at school when quoting Hawkins' joke to some friends. Of course, I had no idea what they meant.
Imagination will often carry us to worlds that never were. But without it we go nowhere. - Carl Sagan
