Theodahad (born c. 480 in Tauresium – died 536) was the King of the Ostrogoths from 534 to 536 and a nephew of Theodoric the Great through his sister Amalafrida.
He might have arrived in Italy with Theodoric and was an elderly man at the time of his succession. Massimilliano Vitiello states the name "Theodahad" is a compound of 'people' and 'conflict'.
He arrested Amalaswintha, queen of the Ostrogoths from 526 to 534, and imprisoned her on an island in Lake Bolsena.
Political instability within the Ostrogothic kingdom served as a pretext to Byzantine general Belisarius to intervene in Sicily and Italy, at the service of the Emperor Justinian, causing the Gothic Wars.
Witiges ordered him killed, and succeeded him as king.
Theodahad had at least two children with a woman named Gudeliva: Theodegisclus and Theodenantha.
A fictionalized version of Thiudahad appears in L. Sprague de Camp's classic science fiction novel Lest Darkness Fall. In the novel, the hero Martin Padway restores Thiudahad to the throne until he is truly unable to rule, when he is succeeded by Uria. The Byzantines are prevented from their near-conquest of Italy.