Soul Stealer

I am not dead; though I would not consider myself alive either.
I am plagued with an affliction that has transformed my life into a confusing state of partial nothingness. I am neither anywhere nor nowhere. The reason I am only partially invisible is because there are certain people who can always see me. Though this may sound pleasing, you are highly mistaken if you assumed so. The only people able to detect my presence, I can hardly even consider people.
They are the most malevolent entities ever to have walked the earth and could only have been spawned from the deepest depths of hell - or that's my theory at least. They appear to take on a human form, but they are not human. They feed off of humans in order to survive in the body they have stolen. They are, The Disembodied.