I was introduced to horror movies at a very young age so I can't really give a specific answer. The first "monster" movie I remember seeing in a theater was KING KONG '76 when I was 2 years old. I slept through most of it. The first (what I would call) true "horror" film I can recall seeing in a theater was THE INCREDIBLE MELTING MAN when I was either 4 or 5 but I'm sure I saw plenty on TV before then on Creature Double Feature, which aired on Saturday afternoons. I doubt my parents would've taken me to the movies if they didn't know whether or not I could handle them first.