Demetrius Augustine Gallitzin was a Russian aristocrat and Catholic priest who served as a missionary in the United States during the early 19th century. Born in The Hague to a noble family, he renounced his vast inheritance to pursue the priesthood. He is famously known as the Apostle of the Alleghenies for his extensive work in the mountain regions. He established the settlement of Loretto, Pennsylvania, which became a significant Catholic community. Today, he is recognized as a Servant of God by the Catholic Church.