Pope John XXIII is most famous for convening the Second Vatican Council (1962-1965), which aimed to modernize Church practices and improve relations with other Christian denominations and religions. His papacy was marked by openness and reform. Birth name: Angelo Giuseppe Roncalli Nationality: Italy Born: November 25, 1881 Died: June 3, 1963 Pontificate: October 28, 1958 – June 3, 1963