Avon's Phantom Witch Doctor (1952) was a unique one-shot...
...with a lead story featuring the title character and a trio of totally-unrelated tales backing it up.
Whether the creature is a Lovecraftian-type Elder-God, a stranded alien, or just a sentient life-force is never really explained.
Another unsolved puzzle is who the writer and artist(s) for this never-reprinted short story were.
But what's life without a few mysteries, eh?