Ungoliant is the primordial being identified as Shelob’s ancestor in J.R.R. Tolkien’s mythology.
Ungoliant appears in The Silmarillion as a gigantic spider-like being who allies with Morgoth, the first Dark Lord. Together they destroy the Two Trees of Valinor, which once illuminated the realm of the Valar. Ungoliant then consumes the light stored in the trees and eventually turns against Morgoth.
Shelob, the giant spider encountered by Sam and Frodo near Cirith Ungol, is described as one of Ungoliant’s descendants. Tolkien therefore connects the frightening creature in The Lord of the Rings to a much older evil from the First Age.
Shelob is not simply another name for Ungoliant. They are separate beings from different periods of the legendarium. Ungoliant’s story belongs primarily to the mythology collected in The Silmarillion, while Shelob appears directly in The Lord of the Rings.