Holy Emperor Theodosios the Great, who convened the Second Ecumenical Council.
St. Theodosios the Great was Roman emperor from 379 to 395. He established the Nicene faith as the faith of the empire, convened the Second Ecumenical Council at Constantinople in 381, and did public penance before St. Ambrose of Milan after the massacre at Thessaloniki.
He is commemorated on January 17.
Feast day
On the New Calendar, Theodosios the Great is commemorated on January 17. Churches on the Old (Julian) Calendar keep the feast on January 30 of the civil calendar.