Sigismund Ernuszt (Hungarian: csáktornyai Ernuszt Zsigmond; c. 1445 – summer 1505) was Bishop of Pécs in the Kingdom of Hungary from 1473 to 1505. He was also Ban of Croatia, Dalmatia and Slavonia from 1494 to 1498. He was the son of John Ernuszt, a converted Jew, who started his career as a custom's duty collector during the reign of Matthias Corvinus, King of Hungary. Ernuszt studied at the universities of Vienna and Ferrara in the early 1470s. The king made him bishop of Pécs. Although the Holy See confirmed him as the administrator of the diocese, he was most probably never ordained bishop. Matthias Corvinus also tasked him with the administration of the newly conquered Archduchy of Austria in 1486.