Moshe Feinstein (Hebrew: משה פײַנשטיין; Lithuanian pronunciation: Moshe Faynshteyn; English: Moses Feinstein; March 3, 1895 – March 23, 1986) was an American Orthodox rabbi, scholar, and posek (authority on halakha—Jewish law). He has been called the most famous Orthodox Jewish legal authority of the twentieth century and his rulings are often referenced in contemporary rabbinic literature. Feinstein served as president of the Union of Orthodox Rabbis, Chairman of the Council of the Moetzes Gedolei HaTorah of the Agudath Israel of America, and head of Mesivtha Tifereth Jerusalem in New York. Widely acclaimed in the Orthodox world for his gentleness and compassion, Feinstein is commonly referred to simply as "Reb Moshe" (or "Rav Moshe"). Source: Wikipedia (en)