Former President Joe Biden called Pope Francis "one of the most consequential leaders of our time" in a statement marking the death of the 88-year-old pontiff Monday. "It is with great sadness that Jill and I learned of the passing of His Holiness Pope Francis,

By the time Francis took over as leader of the Catholic Church in 2013, meetings between the president and the pontiff had become commonplace. During the dozen years that he served as the pontiff, Francis, who died April 21, met each of the three men who served as the U.S. president during his papacy.