Giacomo Boncompagni (also Jacopo Boncompagni; 8 May 1548 – 18 August 1612) was an Italian feudal lord of the 16th century, the illegitimate son of Pope Gregory XIII (Ugo Boncompagni).
He was also Duke of Sora, Aquino, Arce and Arpino, and Marquess of Vignola.
A member of the Boncompagni family, he was a patron of arts and culture.
Pierluigi da Palestrina dedicated to him the first book of Madrigals.
He was also a friend of another composer, Vincenzo Ruffo.