Halloween, Friday the 13th, or anything like that. I was enthralled with the classics; Universal films like Frankenstein, Dracula, and the Creature from the Black Lagoon. Hammer films like Horror of Dracula, Curse of Frankenstein, etc. And of course Tojo films like Godzilla, Godzilla vs. Mothra, King Kong Escapes, and so forth (plus their rival studios' offerings like Gamera!).
And of course there were a lot of other movies in there as well. Science fiction back then was tossed into the horror movie mix with abandon, and vice versa. So include wonders like Planet of the Apes, Silent Running, those wonderful Ray Haryhausen movies, and Colossus: The Forbin Project into the mix.
Of course I was a huge Famous Monsters of Filmland fan, and had a thick stack of magazines in my room, most of which got quite worn over the years. But when I was about 8 years old or so, I got a pair of books about horror movies from a local bookstore, and they were my constant companions. I had completely forgotten the titles (and indeed one title still eludes my memory and my Google skills), but I recently found one on eBay; A Pictoral History of Horror Movies.
To say I had read this book repeatedly when I was just a youngin' is an understatement. These books were my constant companions. I read them and read them and read them, and viewed all the wonderful photos of movies I had seen - usually on Chiller Theater on channel 11 in New York, which showed all sorts of movies from the 30's onwards - and drilled them into my memory.
So when I found that one book, A Pictoral History of Horror Movies, it was like being transported back to 1975. I still remember every picture, every caption, and even a lot of the text. That was a simpler time in horror movie-dom; fewer serial killers (and the ones that were there were kitschy and flashy and usually played by Vincent Price) and more monsters. And I loved it. There's a certain classiness, and of course more than a little self-aware silliness, in there that modern horror movies (which seem to veer more and more into torture porn, body horror, and SHOCK, none of which I particularly like) simply lack.
Hell, I still love it.