The common papal name Pius is derived from the Latin word for 'PIOUS' and is used by several popes throughout history. The most famous of these is Pope Pius XII, who served as pope from 1939 to 1958. He was known for his strong opposition to Nazi Germany and his efforts to protect Jews during the Holocaust. Other notable popes with this name include Pope Pius IX, who reigned from 1846 to 1878, and Pope Pius X, who served from 1903 to 1914.