Vittorio Cassar (Maltese: Vitor Cassar, c. 1550 – c. 1609), born Gio Vittorio Cassar, was a Maltese architect and military engineer. The son of the renowned architect Girolamo Cassar, he was admitted as a knight within the Order of St. John in 1587. He became the Order's resident engineer in the early 17th century, and he directed the upgrading of the Cittadella of Gozo between 1600 and 1603.