Monsignor John Maria Oesterreicher, born Johannes Oesterreicher (February 2, 1904 – April 18, 1993) was a Roman Catholic theologian and a leading advocate of Jewish-Catholic reconciliation. He was one of the architects of Nostra Aetate or "In Our Age," which was issued by the Second Vatican Council in 1965 and which repudiated antisemitism. Based initially in Paris, he condemned the Nazis in weekly broadcasts and writings. He fled to the U.S. after the German invasion of France in 1940.