Euthymius or Euthymios () may refer to:
Saints Euthymius of Perugia, father of Saint Crescentius of Rome Euthymius the Great (377–473), abbot in Palestine Euthymius of Sardis (died 831), Metropolitan of Sardis, Confessor Euthymius the Younger (died 898), monk and hermit who lived on Mount Athos Euthymius the Athonite (), Georgian monk, philosopher, and scholar Euthymius of Tarnovo (1325–1402), Patriarch of Bulgaria Euthymius II of Novgorod (died 1458), Archbishop of Novgorod Euthymius of Dečani, 16th century Serbian monk and martyr Euthymios Agritellis (1876–1921), Greek Orthodox Bishop of Zela, in Amasya, Western Pontus, New Ethno-Hieromartyr
Christian patriarchs Euphemius of Constantinople (died ), also called Euthymius, Patriarch of Constantinople 490–496 Euthymius I of Constantinople ( – 917), Ecumenical Patriarch of Constantinople 907–912 Euthymius I of Antioch, Melkite Patriarch of Antioch Euthymius II of Antioch, Melkite Patriarch of Antioch Euthymius II of Constantinople (died 1416), Ecumenical Patriarch of Constantinople 1410–1416 Euthymius II Karmah (1572–1635), Melkite Patriarch of Antioch 1634–1635 Euthymius III of Chios (died 1647), Melkite Patriarch of Antioch 1635–1647 Euthymius V of Antioch, Greek Orthodox Patriarch of Antioch 1792–1813
Other people Euthymius of Constantinople (11th century), monk Euthymios Zigabenos, 12th century monk and commentator on the Bible Euthymios Malakes ( – before 1204), Greek Orthodox Metropolitan of Neopatras Euthymios Tornikios (), Byzantine ecclesiastical official and writer Euthymius I of Novgorod, Archbishop of Novgorod 1423–1429 Euthymios Saifi (1643–1723), Melkite Catholic bishop of Tyre and Sidon Euthymius Moiseyev (born 1972), Russian Orthodox Bishop of Lukhovitsy