[1] Born in Bologna, son of Bolognese Patricians Boncompagno Boncompagni (1504 - 1587) and wife Cecilia Bargellini and brother of Angela Boncompagni, wife of Girolamo Pepoli, without issue.
22 July 1556 - 23 June 1623), relative of his sister-in-law, and had issue),[2] and another married sibling, children of Cristoforo Boncompagni (10 July 1470 – 1546) and wife Angela Marescalchi, and paternal grandchildren of Giacomo Boncompagni and wife Camilla Piattesi.
[3] He served as superintendent general of the Papal States (Cardinal-Nephew) during his pontificate (1572–85).
He occupied several curial offices (grand penitentiary, prefect of the S.C. of the Tridentine Council).
He participated in the papal conclave, 1585 as a leader of the cardinals created by Gregory XIII.