[3][4] At an early age he entered a monastery, and sometime between 784 and 787, he was ordained as metropolitan bishop of Sardis by Patriarch Tarasios of Constantinople.

[5] Under Emperor Nikephoros I (r. 802–811) he fell into disfavour and was deposed and exiled to the island of Pantelleria off Sicily (ca.

[3][6] The traditional chronology of his death, found both in Byzantine chroniclers (Genesios, John Skylitzes and Theophanes Continuatus) and older historiography and martyrology (cf.

Modern research, however, places it on 26 December 831 on the island of St. Andrew to the north of Cape Akritas on the Bithynian coast south of Constantinople, during the reign of Michael II's successor Theophilos (r.

In addition, several letters by Theodore of Stoudios to Euthymius survive, as well as a panegyric poem in his honour, written by a certain Metrophanes.