Euthymius, called the Enlightener of Karelia and Finland, was a Russian monastic of the early fifteenth century who carried the Christian faith to the peoples of the far north. According to the synaxarion he was born in the second half of the fourteenth century and was drawn to the monastic life from his youth. Around the year 1400 he travelled north to live as an anchorite in the sparsely settled lands along the White Sea.
About the year 1410 several disciples gathered around him and asked him to guide them in the monastic life. On the shores of the White Sea in Karelia, recorded as thirty-four versts from Archangelsk, they built a monastery dedicated to Saint Nicholas the Wonderworker of Myra, with cells for the brethren. Through this community Euthymius is remembered as having brought the Christian faith to Karelia and the surrounding region.
Euthymius died peacefully in the year 1435 and was buried at the monastery he had founded. By tradition he was glorified in 1641, and his relics were uncovered in 1647. He is commemorated on April 18, and is also numbered among the Synaxis of the Saints of Karelia kept on May 21. He is commemorated together with the righteous Anthony and Felix, who are associated with the same monastery.