The Last Roman Consul
On the 7th of November 630 a boy was born. He was christened Flavius Heraclius. On his ascension to the Byzantine throne as co-emperor in 641, aged 11, he took the name Constantine, but is better known as Constans II Pogonatas.
Constans' grand-father Heraclius had ruled during the rise of Mohammed, and the Arabs became an increasing threat during his reign. In 642 they took Alexandria. In 643 Tripoli and much of North Africa fell to them. In 649 an Arab fleet attacked Cyprus; then Crete, Rhodes and Cos. The Byzantine navy was routed at the Battle of the Masts aks the Battle of Phoenix, off the coast of Lycia in 655, with Constans barely fleeing with his life. That the Muslims didn't get further was thanks to infighting amongst their leaders rather to any military skill of Constans' - this is the period that Islam divided into Sunni and Shi'a.
Against the Slavs Constans was more successful, defeating them in the Balkans and re-settling several captured tribes in Anatolia.
In 661 Constans set off for Italy, to fight the Lombards' Duchy of Benevento. He initially won success on the battle field, but was let down by a poorly managed supply train, and ultimately failed to defeat the Lombards.
He next decided to settle in Syracuse, and to make the Sicilian town his headquarters. Strategically this made sense, since the island could be used as a base to re-take North Africa, and to defend Italy from the Arabs, but ... This decision proved to be unpopular with those in Constantinople - they felt they were being abandoned - and with the locals whose resources struggled to supply the court. He was assassinated whilst bathing, and his body returned to Constantinople for burial in the Church of the Holy Apostles.
Constans was neither a great emperor, nor a great general. What distinguishes him is that he was the 'last' Roman consul. The consulship became an imperial title or honor under the empire - rather than the elected office it had been under the Republic. In the 6th century, it lapsed under Justinian. His nephew Justin II held it a couple of times (566 and 568), as did Tiberius II (579) and Maurice (583), once each. In the 7th century it was occasionally revived for emperors - Phocas (603), Heraclius (608 and 611), Heraclonas (639) - but Constans is often cited as the last Roman consul in 642. His son Constantine IV may have held the Roman consulship, but all subsequent Byzantine emperors seem to only have been consul of Constantinople, and the few mentions of Roman consuls are in dubious sources.
What is even more remarkable than a by then empty title, is that Constans visited Rome in 663 - no emperor had done so for over two centuries, since the capital in Italy had moved first to Milan, then to Ravenna.
As with so many Byzantine emperors, we can only identify coin portraits. In the church of Sant'Apollinare in Classe in Ravenna there is however this wonderful mosaic of his son Constantine IV dispensing the Archbishop of Ravenna from taxation.
Coin photo - source.
Map from Wiki showing Byzantine and other lands circa 650.