Saint Theodore was born in Constantinople in 759. He entered the monastic life at a young age and became a deacon and priest, and eventually the abbot of the Studium monastery. He suffered greatly in defense of the holy icons during the iconoclastic period. He reposed on November 11, 826. Together with his brother Joseph, he composed virtually the entire book of the Lenten Triodion.
His feast is celebrated on November 11, and the transfer of his relics is commemorated on January 26.