Pope John XXIII

Pope John XXIII, born Angelo Giuseppe Roncalli, served as the 261st Pope of the Catholic Church from October 1958 until his death in June 1963. He was elected at the age of 76 and is best known for convoking the Second Vatican Council, a major effort to modernize the Church through what he called aggiornamento. His pontificate lasted less than five years and produced the notable encyclicals Pacem in Terris and Mater et Magistra. He was canonized as a saint in April 2014.