Futret/Nightmare Fuel

In addition to the frequent, disturbing-looking album art and bizarre music style; the artist known as Futret has released such gems as Nerves, which features a vocal track from Blackest Eyes by Porcupine Tree.
The lyrics to Upward Infection—which seem to be describing something along the lines of a Mad Doctor—can be unsettling.
The song Cupcakes is already quite disturbing, being all about what an insane Yandere lover would say to you before plunging you to your death. But if you're part of the fandom it is directed to, what is the most scary is not the song itself, but rather, what it represents.