Sisto Riario Sforza was an influential 19th-century Italian prelate from the noble Riario-Sforza family. Born in Naples in 1810, he was ordained a priest in his home city in 1833. He held several significant ecclesiastical roles, including serving as a papal legate in Paris and as the Bishop of Aversa. He eventually became the Archbishop of Naples in 1845 and was elevated to the rank of cardinal in 1846. Throughout his career, he remained a loyal supporter of Pope Pius IX.