Methodius of Thessaloniki

Cyril (Greek: Κύριλλος, romanized: Kýrillos; born Constantine [Greek: Κωνσταντίνος, romanized: Konstantínos]; 826–869) and Methodius (Μεθόδιος, Methódios; born Michael [Greek: Μιχαήλ, romanized: Michaíl]; 815–885) were brothers, Byzantine Christian theologians and missionaries. For their work evangelizing the Early Slavs, they are known as the "Apostles to the Slavs". They are credited with devising the Glagolitic alphabet, the first alphabet used to transcribe Old Church Slavonic.