Pope Nicholas V (Latin: Nicolaus V; Italian: Niccolò V; 15 November 1397 – 24 March 1455), born Tommaso Parentucelli, was head of the Catholic Church and ruler of the Papal States from 6 March 1447 until his death in March 1455. Pope Eugene IV made him a cardinal in 1446 after successful trips to Italy and Germany, and when Eugene died the next year, Parentucelli was elected in his place. He took his name Nicholas in memory of his obligations to Niccolò Albergati. He remains the most recent pope to take the pontifical name "Nicholas".
The pontificate of Nicholas saw the fall of Constantinople to the Ottoman Turks and the end of the Hundred Years' War. He responded by calling a crusade against the Ottomans, which never materialized.