Maybe you are looking for demon?
Interested in Language
Could you suggest another synonym of "fiend"? Does it mean something like an evil wraith?
"I have no name in the regions which I inhabit," replied the voice, mournfully; "I was mortal, but am fiend. I wasmerciless, but am pitiful. Thou dost feel that I shudder."
Fiend is also used as a synom for a spectre or phantom, as well as demon perhaps one of those fits better.
I read enough of that story to know what it is about. (It freaks me out to think about waking up in a coffin.)