Uldor was an Easterling, and one of the sons of Ulfang.

With his father and his brothers Ulfast and Ulwarth, Uldor took service under Caranthir in about First Age 457. During the Union of Maedhros Uldor's false warnings of an attack from Angband delayed the march of the Maedhros' eastern army.

In the midst of the Nirnaeth Arnoediad, Uldor's army, reinforced by Easterlings hidden from nearby, attacked the rear of the eastern Noldorin army. Although this treachery lost the Elves the battle, Uldor was slain by Maglor.

Also called Uldor the Accursed.