Giovanni Garzia Mellini (his first name is also rendered Giangarzia while his middle name is also rendered Garsia) (1562 – 2 October 1629) was a Roman Catholic prelate who served as Cardinal-Bishop of Frascati (1629), Cardinal-Priest of San Lorenzo in Lucina (1627–1629), Camerlengo of the Sacred College of Cardinals (1623–1625), Archpriest of the Basilica di Santa Maria Maggiore (1622–1629), Cardinal-Priest of Santi Quattro Coronati (1608–1627), Archbishop (Personal Title) of Imola (1607–1611), and Apostolic Nuncio to Spain (1605–1607).

[1] Giovanni Garzia Mellini was born to a noble Roman family in Florence, Italy in 1562, the son of Mario Millini and Ortensia Jacovacci.

[1] During the papacy of Pope Clement VIII, he went to France with Cardinal Pietro Aldobrandini to negotiate the marriage of Marie de' Medici to King Henri IV.

[2] He served as Vicar general of Rome (1610-1629) and Secretary of the Supreme Sacred Congregation of the Roman and Universal Inquisition (1616-1629).

[1][2] On 14 April 1627, he received the title of Cardinal-Priest of San Lorenzo in Lucina and Archpriest of the patriarchal Liberian basilica.