pope from 678 to 681. A cleric well-versed in Latin and Greek, he was elected pope in June 678. He judged that St. Wilfrid (Wilfrid, Saint), bishop of York, had been unjustly deprived and ordered his restoration, and he received the submission of Exarch Theodore of Ravenna, whose predecessors had aspired to autonomy.

Through legates, he participated in the sixth ecumenical council (680–681), in Constantinople, which condemned Monothelitism (belief that Christ had only one will) and accepted his definition of two wills, divine and human, in Christ. Agatho prevailed upon the Byzantine emperor Constantine IV to abolish the tax formerly exacted at the consecration of a newly elected pope, which helped establish good relations between Rome and Constantinople. Agatho died during a plague that ravaged Rome.