Theodorus was the archbishop of Ravenna from 677 to 691.^[1]: 304

Consecrated in Ravenna by his suffragans,^{[1]: 283–4 [2]} under his tenure the church of Ravenna reconciled with the Roman papacy, thus ending a period of acrimony during which the Byzantine emperor Constans II, who was a monothelite, directly opposed the Pope by proclaiming the autocephaly of the church of Ravenna in 666.^{[3]: 320 [1]: 283–4}
In fact, in 680 Theodorus adhered to the Sixth Ecumenical Council which condemned monothelitism in favour of the Chalcedonian orthodoxy, thus resubmitting his church to Pope Agatho,^{[3]: 321 [2]} and in 682 he formally renounced to the typus of autocephaly, following the resumption of friendly relations between Constans II's successor Constantine IV and the new Pope Leo II.^{[1]: 283–4}
Writing for the Catholic Encyclopedia, church historian Umberto Benigni claimed that he "was hated by his clergy for having suppressed many abuses among them".^[2]

According to the 9th-century historian Andreas Agnellus, during Theodorus' tenure his namesake Theodorus, exarch of Ravenna, ordered a chapel dedicated to Saint Theodore the Deacon, but of which there is no trace today.^{[1]: 146–7}

Theodorus' stone sarcophagus is located in the Basilica of Sant'Apollinare in Classe,^[4]: 53 along with others belonging to some of his distant successors such as Gratiosus (died c.789). All these sarcophagi were sculpted imitating higher-quality models from previous centuries.^[1]: 289

• Byzantine Papacy
• Exarchate of Ravenna