Pietro Giannone (born May 7, 1676, Ischitella, Naples [Italy]—died March 17, 1748, Turin, Kingdom of Sardinia) was an Italian historian whose works opposed papal interference in Naples.

Giannone graduated in law (Naples, 1698), became interested in the “New Learning,” and wrote the Istoria civile del regno di Napoli (1723; The Civil History of the Kingdom of Naples)—a polemical survey of Neapolitan history in which he espoused the side of the civil power in its conflicts with the Roman Catholic hierarchy. As a result of this, the Istoria was placed on the Index librorum prohibitorum (the papal register of prohibited books), and Giannone was excommunicated. In Vienna, where, until 1734, he received a pension from the Holy Roman emperor Charles VI, Giannone prepared his most important work, Il triregno, ossia del regno del cielo, della terra, e del papa, 3 vol. (“The Triple Crown, or the Reign of Heaven, Earth, and the Pope”). On the transfer of the Neapolitan crown to Charles of Bourbon, (the future Charles III of Spain), Giannone left Vienna for Venice. A suspicion that his views on maritime law were not favourable to the pretensions of the republic, together with clerical intrigues, caused him finally to seek refuge in Geneva (1735). But, while visiting a village in Piedmont, he was kidnapped by agents of the Sardinian government and imprisoned. He wrote his Autobiografia while incarcerated during the last 12 years of his life in the fortresses of Ceva and Turin.