Constantine V (718-775); also known as Constantine the Dung-named; was the son of Emperor Leo III. He succeeded his father in 741; but was almost immediately betrayed by his own brother-in-law Artabasdos; who attacked him while Constantine was crossing Asia Minor to campaign against the Umayyad Caliphate. Constantine was defeated and had to retreat to Amorion; while Artabasdos entered Constantinople and became emperor.

Constantine eventually retook the throne in 743; having his rivals blinded and executed. He became an even more fervent iconoclast than his father; which was what led to the derogatory surname of 'Dung-named'; given to him by religious enemies opposed to his rejection of the veneration of holy images.

Constantine was also an able administrator and general; and waged wars against the Umayyad Caliphate and the Bulgarians. It was while campaigning in the Balkans against the latter that he died in 775; and was promptly succeeded by his eldest son and co-emperor Leo IV.