Person
Ufthak - A victim of Shelob. An Orc in the service of the Tower of Cirith Ungol, under the command of Shagrat. He was captured, poisoned and (presumably) eaten by Shelob, since his fellow Orcs made no attempt to rescue him. Uglúk - One of Saruman’s Uruk-hai. An uruk in the service of Saruman, the leader of the orc-band that captured Merry Brandybuck and Pippin Took at Parth Galen. Underhill Family - A Hobbit-family of Staddle. A common family name among the Bree-hobbits, who lived in the village of Staddle on the east side of the Bree-hill. Undómiel - ‘Evenstar'. Title and surname of Arwen, Queen to Aragorn II Elessar. It usually given in its translated form, Evenstar. Ungoliant - Ancient ally of Melkor. The evil creature of spider-form who was Melkor's accomplice in the Darkening of Valinor, and who fled with him to Middle-earth. The creatures that infested the Ered Gorgoroth were her offspring and descendants, as was Shelob who dwelt on the borders of Mordor. Uruks - The soldier-Orcs of the later Third Age. A term for the large soldiers more fully referred to as Uruk-hai Uruk-hai - The great soldier-Orcs of the later Third Age. The great soldier-Orcs that first appeared in the late Third Age; they were larger and stronger than their forebears, and could withstand the light of the Sun
Places
Udûn - Melkor’s ancient fortress in the far north of the World. "The dark fire will not avail you, flame of Udûn. Go back to the Shadow!"
Words of Gandalf
from The Fellowship of the Ring II 5 The Bridge of Khazad-dûm The Sindarin name of Utumno, the fortress of Melkor in the far north of the World. It was the first and greatest of Melkor's citadels, delved in the earliest days, the home to hosts of demons and monsters. From Udûn, Melkor troubled the world for millennia. From there, he destroyed the Lamps of the Valar, so that Powers left Almaren, their dwelling-place in Middle-earth, and removed into the West. At the time of the awakening of the Elves, though, the Valar attacked Udûn in full force, and destroyed it utterly, carrying its master back to Valinor as their prisoner.
The name Udûn is much less common as a name for Melkor's fortress than the equivalent Utumno. In The Lord of the Rings it appears just once, in Gandalf's quote given above. It survived, though, as a name for the northern valley of Mordor that lay behind the Morannon. No doubt Sauron chose this name in memory of his ancient master's greatest stronghold.
Uttermost West - The lands far across the Western Sea. A name given in Middle-earth to the Undying Lands of Aman in the far west, the dwelling-place of the Valar.