Even if you’re not religious, you’ve got to give religions credit for at least one thing: they really know how to scare the living hell out of people. Religious demons often sound more terrifying than anything a human could dream up, which isn't a bad way to keep potential sinners in line.
This list of demons from religion includes figures from many different faiths. Christianity, Judaism, Buddhism—if it’s got an evil demon, it’s probably here. Some of these are familiar, some of them are obscure, but they’re all really scary.
What happens when you have sex with a mountain? If you answered, “Your union creates a race of rock children, duh,” you’re totally right, but you probably shouldn’t be cheeky, because that’s a really weird thing to know. Asag is a grotesque, hideous demon from Sumeria who leads his rock-children-things in battle. He’s so monstrous to look at, according to legend, he causes fish to boil alive.
An incubus is a male demon that appears to women during erotic dreams. The incubus then attacks the woman by raping her, and subsequent encounters can cause serious illness and death. If you think you’ve got an incubus pestering you, run, don’t walk, to your nearest exorcist.
A Dybbuk is a demon from Judaism, which clings to the soul of a living person and inhabits their body. Dybbuks are said to be the souls of those who cannot pass on to the afterlife because of the totality of their evil. They enter a person when they have sinned and not atoned, leaving a door open for demonic influence. So if you don’t want a demon possessing you and wrecking your life, just don’t sin. Should be easy, right?
As Lucifer’s right-hand man, Mephistopheles does the Devil’s bidding. He collects souls that have been damned and bargains with those who wish to sell their souls. Mephistopheles comes from the classic German legend of Faust, who sold his soul to the Devil in exchange for infinite knowledge and magical powers.