Ungoliant was a primordial being in the shape of a gigantic spider and one of the most terrifying evil spirits in the Lord of the Rings universe. She originally made her lair in one of the most secret, dark, and unexplored area of Arda: Avathar. She made her way further and further North, consuming more and more light which she both hated and hungered for. Melkor sought her out to aid him in his plot for vengeance against the Ainur and Valar. Melkor and Ungoliant plotted there to sneak into Valinor and destroy the Two Trees: Laurelin and Telperion, which together gave light to Valinor. Ungoliant agreed to help him only after Melkor promised her that she would also have all that she could lust for if she hungered more after the Trees' destruction, and that he would give freely of both hands.
Ungoliant concealed them both by weaving a cloak of darkness about them, allowing them to approach the trees unseen. Melkor then stabbed at the trees with his spear deep into their core so that Ungoliant could drink their sap until they were drained and whithered. She then went on to consume the Wells of Varda, letting her grow to an absolutely ginormous size such that even Melkor feared her. They then fled North to Melkor's abandoned fortress of Angband.
On their way, Melkor also came upon the home of Fëanor in Formenos, and stole all the gems and riches of the Ñoldor including the Silmarils. As they continued to flee North, Ungoliant would not leave Melkor for she still hungered and demanded to have all the gems of the Noldor. Melkor reluctantly gave all but the Silmarils for her to consume, yet she was still not sated. She demanded the Silmarils from Melkor, yet he refused.
Ungoliant was now far greater than before now that she had consumed so much, and she attacked Melkor, strangling him in a massive web. Melkor let out a terrible cry so loud and dreadful that it awoke the Balrogs from their slumber to protect their master. So, with the arrival of the Balrogs of Morgoth, Ungoliant fled south.
She then laid down under the mountains of Ered Gorgoroth where she bred with other spider-like forms there to create more monstrous spider offspring, probably including Shelob. Her fate is unknown, though she is rumored to have devoured herself, leading to her death. Otherwise, she likely died during Dagor Dagoroth.
Powers and Stats
Tier: Unknown | At least 4-A, likely 3-B
Origin: Lord of the Rings
Age: As old as the universe itself, possibly older (She might be one of the Nameless Things, who are older than the Ainur)
Classification: Giant demonic spider (Her true origin is unknown, though she is said to be some kind of primordial force of darkness. Possibly a Nameless Thing)
Attack Potency: Unknown (Took the full power of up to seven Balrogs in order to chase her off) | At least Multi-Solar System level, likely Multi-Galaxy level (Grew to such size that even a slightly weakened Melkor, whom she later overpowered, was terrified of her. Even while further weakened, Melkor's power was still the greatest of all things on Earth, making him stronger than the Valar. Consumed the Two Trees, of which a single flower/fruit made the Sun and Moon. However, they are likely smaller than their real world counterparts. Devoured the contents of the Wells of Varda, which contained all the light of the Two Trees and out of which was made the stars)
Lifting Strength: Unknown | Unknown
Striking Strength: Unknown | At least Multi-Solar System Class, likely Multi-Galactic
Stamina: Unknown | Unknown
Standard Equipment: None notable
Intelligence: While she is certainly sentient, she seems to be motivated by little more than a limitless hunger
Weaknesses: Needs to eat an absolutely massive amount in order to sustain her power or she'll weaken from hunger (Rumored to have eaten herself, which was how she died. However, this has never been verified)
Key: Weakened | Full power