Re: The Cthulhu Mythos
Cthulhu is also pure dobbin evil in ball that can't be defeated.
I've read a Lovecraft story where Cthulhu plays the integral part, but that's been at least 3 years ago. There's normally a (possibly brainwashed) cult that lives under the guise of a secret society (or the like) that worships it as their god. And for centuries have been waiting for the right time to open the portal to unleash Cthulhu, the destroyer who will bring eternal darkness, or something along those lines. That's actually where I got the idea for my "And as the Wind Blows" for the evil cult story (probably haven't read it, twas a LOONG time since I posted anything lol).
Other than that--I recommend finding a Lovecraft short story collection and reading the story with Cthulhu mentioned in it.
Fact, not Opinion: Lovecraft is the best classic horror writer.