I’ve had my share of such interests, including:
Love at First Bite
The Labrynth
The Creepshow
The Rocky Horror Picture Show
Nightmare on Elm Street movies
When I was younger, I was obsessed with particular scenes in the movie The Dark Crystal.
I also had “composite interests” around media entailing groups of movies/tv shows that I was obsessed with as a group (and perceived as being actually related and mutually entailed in some way that is impossible for me to explain), such as the Star Wars series Krull, and the tv shows Star Trek, Battlestar Galatica, Buck Rogers in the 25th Century, Blake’s Seven, Tomorrow People, Saphire and Steel, Doctor Who, Tron, the Pigs in Space skitz on the Muppet Show, and a cartoon that involved some plant species attacking earth… there were a few other shows/movies involved in that particular grouping that I cannot remember meaningful specifics for (I’d know them if I saw them).
When I was even younger still, I was obsessed with the name for a movie (from a book) called “Watership Down” (or something that sounded like that to my inept audio processing), and with the theme song from this movie (Bright Eyes I think it was called). I thought there was either some water related space ship or a big “olden day” sailing ship entailed in this movie, (either was fine with me as I had a liking for both space ships and anything to do with the“olden days”). I was mystified and disappointed beyond belief when I finally saw the movie on tv and neither space ship nor “olden day” sailing ship appeared.