Samael the demon

I am Samael, the son of many and without kin. I exist within the wicked-minded and the diseased
~ Samael to his prey

Our Father who art in Heaven... YOU STUPID MORTAL!
~ The victim to Samael
(menacing silence)
~ Samael

Samael is the antagonist of the titular Creepypasta story. Samael is a demon who is drawn to wherever there has been a murder.

Samael would say he exists in the evil minds, and then if challenged by a human who says he is mortal, Samael opens up his black robes, revealing his diseased, corpse-like body beneath. Samael will send a pack of Hellhounds to chase down the victim if he runs, and then Samael will pursue the victim to his home. If the human finds his door open, then Samael is inside, and they can never enter. If the door is shut, they may enter.  If they see Samael once inside, then they should kill themselves.

A way of avoiding Samael altogether is to find a refuge in a church until daybreak.