My chosen sub-genre is "possession". Perhaps the most well known example of this is the 1973 film "The Exorcist". Films of this genre play on the fear of the unknown, superstition, and the idea that evil forces exist in the world. This can work in a number of ways (spirits, demons, ghosts or witches). The characters fall to an evil force that is trying to victimise or corrupt them in some way. (e.g Blair Witch Project, in which the witch is taking vengeance for them trying to expose her)
In my research, i looked at the films that are regarded to be the best in this sub-genre, here is a list of them:
http://horror.about.com/od/horrortoppicklists/tp/Best-Demonic-Possession-Movies.htm
