Porzia de' Medici (1538–1565) was an Italian missionary and illegitimate daughter of Alessandro de' Medici, Duke of Florence and an unknown mother. She was born after the assassination of Alessandro and was placed as a young child in the Augustinian convent of San Clemente in Via San Gallo. The convent was founded by Maria Salviati, the mother of Cosimo I de' Medici, to shelter the illegitimate daughters of Alessandro. Porzia took her final vows and became a Roman Catholic nun. Eventually she became the abbess of the convent.