Cosimo de' Medici (27 September 1389 – 1 August 1464) was an Italian statesman, ruler of the Florentine Republic during the Italian Renaissance, and head of the Medici family. He was a close friend of Ilario Auditore, who served as Gonfaloniere to Cosimo during his reign. Cosimo was also the grandfather of Lorenzo de' Medici, and founded the Medici bank.
Worried about the rising influence of Cosimo de' Medici, the Albizzi, a rival Florintine banking family, had him imprisoned in the Palazzo della Signoria. Gaining influence behind the scenes, Cosimo rose to power in 1434 and exiled the entire Albizzi family except for Luca, who had been loyal to him.