Marco Cornaro (1482 – 24 July 1524) (called Cardinal Cornaro and Cardinal Cornelius) was an Italian Roman Catholic cardinal and bishop.
A member of the House of Cornaro, Marco Cornaro was born in Venice in 1482, the son of Giorgio Cornaro and Elisabetta Morosini. He was the nephew of Catherine Cornaro, Queen of Cyprus. His older brother Francesco Cornaro was also a cardinal. Early in his life, Marco Cornaro was a protonotary apostolic.
Pope Alexander VI made Cornaro a cardinal deacon in the consistory of September 28, 1500. He received the deaconry of Santa Maria in Campitelli on October 5, 1500.
He arrived in Rome on September 1, 1503 and then participated in both the papal conclave of September 1503 that elected Pope Pius III, and the papal conclave of October 1503 that elected Pope Julius II.
On November 29, 1503, he became apostolic administrator of the see of Verona, occupying this post to his death. He was elected Bishop of Famagusta on December 11, 1503; he resigned this see on July 1, 1504. In July 1506, he was named titular Latin Patriarch of Constantinople, holding this see until October 30, 1507, and then again from June 11, 1521 until his death. In January 1511, he accompanied Pope Julius II during the siege of Mirandola. The pope then named him papal legate to the Patrimonium Sancti Petri, holding this position until 1514. He was also involved in the negotiations to reconcile the Republic of Venice with Pope Julius II.