Theodoric the Great, (454?–;526), founder of the Ostrogothic kingdom in Italy. Under Theodoric's father the Ostrogoths became allies of the Eastern Roman (Byzantine) Empire, and Theodoric spent his youth in Constantinople. He succeeded his father as king of the Ostrogoths in 474. In 488, when he threatened to attack Constantinople, the Byzantine emperor persuaded him that Italy offered much richer plunder. Theodoric redirected his forces into Italy, which was under the rule of the German-born general Odoacer. By 489 Theodoric's Ostrogoths were in possession of all of Italy except the capital city of Ravenna. In 493 Theodoric persuaded Odoacer to surrender Ravenna; in exchange he agreed to rule Italy jointly with Odoacer. A week later, however, he murdered Odoacer at a banquet and became sole ruler.

Theodoric's reign, which lasted for 33 years, brought peace and prosperity to Italy. The king's strong army and wise foreign policy kept his lands free from invasion. He preserved Roman traditions, constructed public buildings and made many public improvements, aided agriculture, and encouraged art and literature.

The last years of Theodoric's reign were marred by religious controversy. Theodoric was an Arian (one who believed that Jesus Christ was created by God and was thus inferior to him), but he extended toleration to all religions practiced in his realm. In 523, in reaction to persecution of the Arians by Justin I, the Eastern Roman emperor, Theodoric ceased his policy of toleration. In 524 he executed the philosopher Boethius, whom he incorrectly suspected of conspiring with Justin to overthrow him. In 525 he sent Pope John I to Constantinople to persuade Justin to end his persecution of Arians. John, who was himself opposed to Arianism, failed and Theodoric had him imprisoned.