According to tradition, the first Doge of Venice was a man called Paoluccio (or Paolo Lucio) Anafesto. Venice at that time was part of the Byzantine Empire, ruled by the Emperor Phillipikos Bardanes, and was administered by a tribune appointed annually. This was a dangerous time for the region. It was constantly under attack by the lombards, people from outside the Empire who had already settled in northern-Italy and sought to expand further. The system of annual tribunes produced weak leadership at a time when a strong leader was necessary.
The Patriarch of Grado, up the coast from Venice, in the direction of modern Slovenia, decided to call a conference in the nearby town of Eraclea, to elect a dux (leader) for life to provide the leadership the area was lacking. Paoluccio, a well-respected native of Eraclea, was elected. The title Doge derives from this original latin title of dux.
It’s unclear whether Dux Paoluccio was truly independent (as later Venetians insisted he was) or under the command of the Exarch of Ravenna, the most important Imperial official in northern-Italy.
Paoluccio was listed as the first doge throughout the time of the Venetian Republic, however, in recent years historians have argued about whether he really existed. There have been attempts to conflate him with other contemporary characters, such as Exarch Paul of Ravenna and the Duke of Treviso, who was actually one of the lombard invaders. There is also an argument as to his true dates.
Tradition however, maintains that he was Doge for twenty years from 697, although it cannot agree over how he died. Some cite old age, and some cite a rebellion that led to the installation of his successor, Marcello Tegalliano.