Strange Horizons has a list of Horror Stories They See Too Much Of to complement their list of science fiction slushpile cliches.
1 Serial killer or vampire stalks and slays victim(s).
i. The tables are turned at the end. (For example, the intended victim turns out to be a vampire or other powerful supernatural creature.)
ii. The serial killer is insane.
iii. The serial killer is under supernatural influence.
iv. The serial killer was abused as a child.2 Person is insane, and kills a lot of people because of it.
i. The insanity is due to supernatural influence.
ii. The insane person does property damage instead of killing people.
(via Ober Dicta)
