Theodotus of Ancyra was a fifth-century bishop and theologian residing in Ancyra, which is known today as Ankara. During the reign of the Byzantine Emperor Theodosius II, he participated in the Council of Ephesus in 431. Although he had previously aligned himself with the Nestorian theological views held by Nestorius, the bishop of Constantinople, he changed his position during the council to support Patriarch Cyril of Alexandria. This decision led to his condemnation by the Nestorians at the Synod of Tarsus in 432.