I decided to revive this thread with Bloodstained taking demons from the Lesser Key of Solomon, it means more origins I can dig into.

Anyway, here's a relatively simple one, Astarot:
His name is derived from the Canaanaite goddess Ashtoreth, known in Greek as Astarte, who was known by the Babylonians as Ishtar and by the Sumerians as Inanna. She was a fertility of some kind. Later demonized in Judeo-Christian sources, I believe she is mentioned in the Old Testament.
I also think I found out why exactly all these demons from the grimoires look the way they do (i.e very bizarre). It seems to be a bit of a complex system involving the letters of their names being tied to certain images of celestial bodies. A lot of grimoires linked demons and angels to celestial bodies, like for example, Angel X being a "spirit of Jupiter" or something. Certain celestial bodies had certain characteristics for their images, a king riding on a wolf, an owl, a young woman, and so on. So it appears a lot of demons seem to have adopted these traits. It seems to have its origin in Heinrich Cornelius Agrippa's "Fourth Book of Occult Philosophy", which contains section explaining how it works, but it could be older.
Interesting. On the note of the Ghoul, I'm curious, are there any instances in CV you know of (because I can't think of any) where the Si'lat is referenced?
I'm so sorry, I completely missed this post for some reason. I can't think of any instances out of the top of my head, but I'll let you know if I find anything.