List of heads of state of Florence

The first de facto Lord (Signore) in the history of the Republic of Florence was Cosimo de' Medici. Thanks to his moderate policy, Cosimo managed to maintain power for over thirty years until his death, ruling the state silently through his trusted men and thus allowing the consolidation of his family, the Medici, in the government of Florence.

In 1532, to reinforce and formalize the Medici rule in Florence, Pope Clement VII, himself a Medici, created the title of Duke of the Florentine Republic to Alessandro de' Medici. With the creation of the new title it abolished the age-old signoria (elective government) and the office of gonfaloniere (titular head-of-state elected for a two-month term) and replaced it with three institutions: the consigliere, the Senate and the Council of Two Hundred.

Background
From its creation in the 12th century until the first decades of the 15th century, the city-state of Florence was ruled by a series of democratic governments, such as the Consul, Podestà and most notably by a council known as the Signoria of Florence. The signoria was chosen by the gonfaloniere (titular ruler of the city), who was elected every two months by Florentine guild members. Not having until that moment fallen into the hands of powerful dynasties as happened in several other Italian states. This situation completely changed with the rise of the Medici family, in that period owners of the largest European bank, and the wealthiest family of that era, which made the dynasty accumulate immense influence in the city, even without holding public offices.

Medici lords of Florence, 1512–1532
After the Sack of Rome, Florence overthrew the Medicis once more and became a republic until Pope Clement VII signed a peace treaty with Charles V, Holy Roman Emperor who then invaded Florence and restored the Medicis.