Francesco Girolamo Cancellieri (Rome, October 10, 1751 – Rome, December 29, 1826) was an Italian writer, librarian, and erudite bibliophile.
Thomas Adolphus Trollope wrote a summary of his biography, which had been extracted were published by a Giuseppe Beraldi in a series called Memorie di religione, di morale, e di letteratura. Francesco's paternal family was from Pistoia originally; his father had been a secretary to Cardinal Paolucci. Francesco was dispatched to be educated by the Jesuits at the Collegio Romano, though he never took vows as a priest. He was employed as secretary for various diplomats in Rome. However, in 1773, he lost important backers when the Suppression of the Jesuits was declared by Pope Clement XIV.
In 1775, Cancellieri was appointed librarian for Cardinal Antonelli, whose library was located in the Palazzo Pamphili in Piazza Navona; this post Cancellieri held till the latter's death in 1811. He lived on No. 63, Via del Mascherone, in a small house adjacent to the church of San Petronio dei Bolognesi. In addition to librarian position, Cancellieri was also Superintendent of the Propaganda printing press, and for a time, Prosigillatore for the Vatican, (Deputy Sealer of Briefs). But the income from these positions was paltry, and for years he was close to insolvency, specially after his protector, Antonelli, died. His publications rarely brought in income, and were often sponsored by those to whom they were dedicated.
In his position as secretary, Cancellieri proved prolific, writing nearly three hundred treatises or books. He was equally a prodigious epistolarian, he sent over 300 letters alone to the historian Tiraboschi. He was amiable and neat in person and language, but never terse; and his style in manners and writing were bountifully steeped with gushingly effusive, but also often grating, cordialities. The poet Leopardi complained that: