wikipediaConstantine III (Greek: Κωνσταντῖνος Γ΄; Latin: Heraclius Novus Constantinus Augustus; 3 May 612 – 20 April or 24/26 May 641) was Byzantine emperor for four months in 641, making him the shortest reigning Byzantine emperor. He was the eldest son of the Byzantine Emperor Heraclius and his first wife Eudokia.
Constantine's birth name was Heraclius Novus Constantinus, (Greek: Ἡράκλειος νέος Κωνσταντῖνος), which was also the official name under which he reigned. The name Constantine became established in later Byzantine texts as short for the Emperor and has become standard in modern historiography. In terms of official imperial nomenclature, the style "Constantine III" would be more appropriate for his son Constans II (r. 641–668).