Uldin or Uldes (died 412) was one of the primary chieftains of the Huns located beyond the Danube during the reigns of the Eastern Roman (Byzantine) Emperors Arcadius (394 – 408) and Theodosius II (408 – 450). He did not, however, have total control of the Hunnic people, but was a leader of the state's western wing.

He first became known to the Romans in December 400, when he decapitated Gainas, and sent the head to Arcadius as a gift. Five years later, Uldin headed a body of Huns, together with his allies the Sciri, in the service of the western Roman Magister Militum, Stilicho, against the invasion of Goths under Radagaisus.

Uldin's invasion of Moesia in 408 was repulsed, with thousands of his Germanic allies falling into Roman hands. Uldin was forced to retreat.

Uldin died in 412, whereafter the Huns split into three large groups.

In the Scandinavian sagas Uldin is called Odin, the sagas recite the coming of Odin with a force of the Turkic people called Ases, and his establishing the state Asaland and a series of Scandinavian dynastic lines, including the lines of Yngling, Uppsala, and Vestfold. According to the Scandinavian sagas and archeological excavations of the Gamla Uppsala burial kurgans, Uldin died in Sweden at around 450 CE. In Scandinavia, Uldin was deified as a progenitor Odin.