Giuseppe Antonio Sassi, Latin: Saxius (28 February 1675 – 21 April 1751), was an Italian librarian and literary scholar.
After completing his studies, he joined the congregation of the Oblates of Saints Ambrose and Charles and taught literature.
After receiving his doctorate at the Ambrosian College, he was appointed rector in 1711 and curator of the famous library founded by Cardinal Federico Borromeo.
He contributed to the publication of Muratori's Rerum italicarum Scriptores with notes and essays and with transcripts from the manuscripts in the Ambrosian library, including History of the Goths by Jordanes, the Chronicles of Landulf the Younger, Ottone & Acerbo Morena's City of Lodi, the Life of Dolcino, a Novarese heresiarch, and of the History of the Visconti, by Galvano Fiamma.
He also revised and enriched with notes the History of the Kingdom of Italy (De regno Italiæ), by Sigonius, and inserted it in the second volume of the complete edition of this scholar's works.