Theodosius III (-c. 754), also spelt Theodosios III, was a financial officer and tax collecter in the Byzantine Empire, with some claiming him to be the son of former Emperor Tiberios III. When the Opsikion troops rebelled against Emperor Anastasius II, they declared Theodosius emperor, a choice he did not readily accept. According to one story he even tried to hide in the forests near Adramyttium before being found and acclaimed emperor in 715.