Euthymius I of Constantinople

Euthymius I was Patriarch of Constantinople from 907 until 912.

Euthymius became a monk at a young age. He served as confessor to Byzantine emperor Leo VI. He was promoted to the throne of Saint Andrew by the latter after Patriarch Nicholas Mysticus refused to allow Leo to marry for a fourth time.

In 912, emperor Leo VI died. His successor, Alexander III, reinstated Patriarch Nicholas and defrocked Euthymius.

Euthymius died on August 5, 917, in the monastery of Agathos. He was subsequently canonised a saint. He is celebrated on August 5.