Constantine (Greek: Κωνσταντῖνος, 820s or 830s – before 836) was an infant prince of the Amorian dynasty who briefly ruled as co-emperor of the Byzantine Empire sometime in the 830s, alongside his father Theophilos.

[3][a] As Theophilos had succeeded Michael II on 2 October 829, Constantine was heir to his father's throne and was crowned co-emperor a short time after his birth.

[1] The historian Lynda Garland argues that Constantine was born in 834 and died when he was two years old, assuming that he was crowned immediately after his birth.

The historian Warren Treadgold states that Constantine died around 835;[11] he must have died by 836, since in that year Theophilos was recorded as being without a male heir (Constantine's younger brother Michael III would be born in 840),[1] a situation Theophilos attempted to rectify by marrying his infant daughter Maria to general Alexios Mosele, who shortly before this (possibly as early as 831) had been promoted to caesar (heir to the throne).

[12] According to the Theophanes Continuatus, a collection of writings likely penned in the 10th century, Constantine died by drowning in a cistern at the Palace of Blachernae after escaping the care of his nurse.