(March 27, 1714 – October 10, 1795) was an Italian theologian, historian, and prolific writer.
Zaccaria taught grammar, the humanities, and rhetoric in the College of Gorizia, and was ordained priest at Rome in 1740.
He spent some time in pastoral work in Ancona, Fermo, and Pistoia, gaining renown as a preacher and controversial lecturer.
In 1751 he succeeded Muratori as ducal archivist and librarian of Modena, but was removed in 1768, owing to his Antifebronio, in which he strenuously defended the rights of the Holy See.
Clement XIII allowed him an annual pension, continued under Clement XIV, and increased by Pius VI, who appointed him professor of church history at the Sapienza and director of the Pontifical Ecclesiastical Academy.