Ungoliant

Ungoliant is a fictional character in J. R. R. Tolkien's Middle-earth legendarium, described as an evil spirit in the form of a spider. She is mentioned briefly in The Lord of the Rings, and plays a supporting role in The Silmarillion. Her origins are unclear, as Tolkien's writings don't explicitly reveal her nature, other than that she is from "before the world". She is one of a few instances, along with Tom Bombadil and the Cats of Queen Berúthiel, where Tolkien does not provide a clear background for an element of his fiction.