Marie-Alphonse Ratisbonne, N.D.S., (May 1, 1814, Strasbourg, Alsace, France – May 6, 1884, Ein Karem, Mutasarrifate of Jerusalem, Ottoman Empire) was a French Jew who converted to Catholicism and became a Jesuit Catholic priest and missionary. He later was a co-founder of the Congregation of Our Lady of Sion, a religious congregation dedicated to the conversion of Jews to the Catholic faith.