Ungoliant is a fictional character in J. R. R. Tolkien's 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 do not 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.
Ungoliant means "dark spider" in Tolkien's invented language of Sindarin. It is a loan word from Quenya: Ungwë liantë. She is also known as Gloomweaver (Sindarin: Gwerlum, Quenya: Wirilomë).
Tolkien's original writings say that Ungoliant was a primeval spirit of night, named Móru, who aided Melkor in his attack upon the Two Trees of Valinor, draining them of their sap after Melkor had injured them. She also consumed the reserves of light from the wells of Varda. Afterward the light of the trees persisted only within the Silmarils of Fëanor. Ungoliant helped Melkor evade the Valar by shrouding them both in the impenetrable darkness produced by herself.
Evil incarnate from the depths of night,
a monstrous creature that hungers for light.
Corrupted by Melkor to do as he says,
this hideous spider, unwillingly obeys.
Telperion and Laurelin shone brightly this night,
these trees of the Gods, created for light.
All around Valmar shone silver and gold.
Melkor seen this and his heart grew cold.
Over the fields of Valinor she came;
the fear of Melkor drove her insane,
to the mound where the trees did grow.
Melkor struck both with a mighty blow.
Their sap poured forth as if it were blood.
Ungoliant drank as fast as she could.
All across Valinor darkness did reign.