There are certain movies that always sort of get called horror movies, but aren’t really horror movies but people discuss them as if they were or weren’t horror movies. For example Alien. There really isn’t much to call this a horror movie. It takes place in space, involves a literal alien species that takes over a space ship. This is all typical and known sci-fi territory in every sense of the genre. Many times however it gets tossed into the horror section. Here for example Nerdist list as a space horror movie. I have had this argument with @torstenvblog for years actually. But realistically aside from “it scared some people” I have never gotten a real answer on how its a horror movie.
Another one I have heard, and made a list of 70 best horror movies is Jaws (1975) A thriller about a man-eating shark somehow quite often gets tossed into the horror movie category because simply, it scared people. What we really need is some sort of check list to decide this on. Is something being scary simply what decides it? Because plenty of horror movies didn’t scare me so are they no longer horror movies? Clearly being scary isn’t enough imply on the grounds of that being subjective. I also am not sure that simply having a monster won’t do it. Godzilla is a monster and nobody would call those monster movies.
Realistically I think we need to have a few things in place, for example there needs to be some sort of otherworldly or super force in play. Think werewolf or vampire or maybe Freddie/Jason sort of deal. A natural entity such as a shark or Alien alone doesn’t seem to be enough.
On the other side of things, a movie should also be making the attempt to be scary on some level, obvious exceptions are when something is trying to be funny or is clearly setting up something for later. Nobody expects horror movies to be scary constantly. Jaws was a suspenseful movie and had some jump scares, but the movie was never really designed to truly make you scared the same way most horror movies are.
Now I am not pretending to be an expect or to by any means simply dismiss new variations of the horror genre. In fact I love them, but this idea that anything that is scary equals horror movie makes very little sense to me. It is like saying anything that has a funny moment is a comedy which is something nobody ever says.
Anyway, I truly think it is time we recognize that movies like Jaws and Alien are great and classic movies, they simply are not horror movies. Best wishes and may the gaming gods bring you glory.