(b Rome, Dec 11, 1529; d Rome, May 18, 1600).
Italian antiquarian and collector. He was an illegitimate son of the Orsini family. He devoted himself early to the study of manuscripts under the guidance of Gentile Delfini, Cardinal Ranuccio Farnese’s Vicario at S Giovanni in Laterano, Rome. In 1554 he became a canon of the same church, and on Delfini’s death in 1559 entered Farnese service, in which he remained for the rest of his career.
Orsini was secretary and librarian to Ranuccio Farnese until the latter’s death in 1565. He was then ‘inherited’ by Cardinal Alessandro Farnese (see Farnese family §(3)) as librarian and as keeper of the antiques and works of art in the Palazzo Farnese. Orsini fulfilled his duties with care, acquiring many new works for the Farnese collection and advising his patron on the choice of artists for several commissions. He also composed inscriptions for the Cardinal’s frescoes and devised iconographic programmes, including that for the Sala d’Ercole in the Villa Farnese at Caprarola....