Theodoric (Ger. Dietrich), surnamed the Great, king of the Ostrogoths, born in Pannonia about 455, died in 526. He was the son of Theodemir, one of the chiefs of the Ostrogoths settled on the banks of the Danube, and when eight years old was sent as a hostage to the court of Constantinople. At the age of 18 he was restored to his father, and, after greatly distinguishing himself in war, he succeeded him as sole king of the Ostrogoths in 475. The southern part of Pannonia and Dacia had previously been ceded to them by the emperor Zeno the Isaurian, of whom Theodoric was for some years a faithful ally; but the emperor broke his promises, and Theodoric ravaged the Byzantine territories till 483, when Zeno conferred upon him large gifts and many honors, and in 484 he named him consul. The war was renewed in 487, and Theodoric marched upon Constantinople; and to get rid of him Zeno proposed to him the invasion of Italy, then ruled by the usurper Odoacer. Consequently in 488 he marched toward the peninsula at the head of his whole people, amounting to about 200,000, with a large number of wagons.
He first met in the Alpine passes and routed an army of Gepidao and Sarmatians, then defeated Odoacer himself on the banks of the Sontius (Isonzo) in 489. After two other victories, one on the banks of the Adige and the other on those of the Adda, he shut his opponent within the walls of Ravenna, and after a siege of three years received his capitulation in 493, apparently consenting to share the kingdom of Italy with him; but Theodoric soon after had his rival assassinated at a solemn banquet, and firmly established his power over the whole peninsula. He distributed one third of the lands to his soldiers in military tenures, but preserved as far as possible the administrative organization of the Roman empire. Un-der his fostering care Italy became prosperous again; agriculture and industry revived; literature and the fine arts flourished; internal improvements went on, and new monuments were erected. Through well devised alliances, he controlled nearly all the barbarians that had settled in western Europe. He checked the triumphant progress of Clovis after the victory of Vouille in 507, protected the Visigoths, and secured for himself the possession of Provence. His latter years were embittered by religious troubles.
The Arians, to which sect he belonged, being persecuted in the East, he retaliated against the Catholics of Italy; this brought on a conspiracy, in which the philosopher Bo-ethius, a great favorite with him, and the venerable Symmachus were apparently involved, and in a moment of passion he ordered them to be put to death. Their innocence being afterward demonstrated, remorse preyed upon his mind and hastened his death. He is the Dietrich of Bern of the Nihelungelied.