Constans II Heraclius Pogonatus (November 7, 630–September 15, 668) was Byzantine emperor from 641 to 668. He was the son of Constantine III, and due to the rumours that Heraclonas and Martina had poisoned Constantine III he was named co-emperor in 641.
Under Constans, the Byzantines completely withdrew from Egypt, and the Arabs launched numerous attacks on the islands of the Mediterranean Sea and Aegean Sea. Constans sent a fleet to attack the Arabs at Finike in 655, but was defeated; the Arabs were preparing to attack Constantinople, but didn't carry out the plan when civil war with the Shiites broke out among them. In 658 he defeated the Slavs on the Danube River, temporarily slowing their advance throughout the Balkans.
He wanted to avoid the succession problems of his own reign, so he had his brother Theodosius murdered and named his sons Constantine, Heraclius, and Tiberius co-emperors. In 661 he campaigned against the Lombards in Italy and reportedly decided to move the capital of the empire to Sicily. This proved to be a very unpopular decision. On September 15, 668 Constans was assassinated in his bathroom by his chamberlain. Constantine succeeded him as Constantine IV.