Ghosts. One of the most fundamental tools of the horror genre. Supernatural horror movies, shows, stories, and art are a natural direction because the return of the living in a much less corporeal seems reasonable and logical. And scary.
And if it isn’t a loved one returning, that can have even more profound ramifications. If a malevolent being comes to you and is not physical, how in the world do you protect yourself?
Supernatural tales are as old as storytelling. And they merge with many other subgenres and tropes. Any time a monster is not physical or a harbinger of doom appears that cannot be explained from something physical, you’re working with the supernatural.
Related Genres and Tropes
Psychological Horror | Witchcraft Horror | My House is Scary | That House is Scary | Ghosts are Scary