Totally a personal opinion and subject to change but here’s a list of the top 5 terrifying demons I could think of. Shout out in the comments to add to this list. We’ll be building more later.
Pazuzu was made famous by the movie “The Exorcists” where it possessed young Regan MacNeil. It’s said to have the head of a lion, the wings of an eagle, and the body of a man. Considering that The Exorcists is loosely based on true events it’s no wonder Pazuzu is considered terrifying.
Malphas commands forty legions of demons in Hell’s army, all entirely at his command. He’s said to have the ability to reveal your desires and destroy them at will. He will betray you but only after accepting your blood. He’s considered the grand president of Hell and is second in command only to Satan himself.
First introduced in the book of Revalation, Abaddon in Hebrew means “place of destruction” and he surely does not disappoint. According to Christian theology Abaddon is the king of the bottomless pit. This pit holds the lost souls of humanity. In other theological texts Abaddon is depicted as the demon (or angel) of destruction, a dominant figure of the Apocalypse, and one of the chief demons of hell that in many cases refuses to obey even Satan.
Samael, once considered an Archangel in Judaism, is something of a paradox. Though not considered “evil” like other demons of lore he’s considered incredibly fierce and not an entity you would want to piss off. His wrath in some writings is legendary.
Mephistopheles was once a low ranking demon that climbed the ranks in hell. He’s a complete and obedient servant of Satan. He is said to have a human body, long nails like a witch, the frightening face of a monster, and wings like an angel. Not a good-looking guy any way you look at it.