The pope also known as the supreme pontiff (from Latin 'pontifex maximus' "greatest priest"), is the Bishop of Rome and 'ex officio' leader of the worldwide Catholic Church. Since 1929, the pope has also been head of state of Vatican City, a city-state enclaved within Rome, Italy. The current pope is Francis, who was elected on 13 March 2013, succeeding Benedict XVI.

During the 20th century there was a total of nine popes that held the post. They were"

Leo XIII 20 February 1878 – 20 July 1903 (25 years, 150 days)

St Pius X 4 August 1903 – 20 Aug 1914 (11 years, 16 days)

Benedict XV 3 September 1914 – 22 Jan 1922 (7 years, 141 days)

Pius XI 6 February 1922 – 10 Feb 1939 (17 years, 4 days)

Pius XII 2 March 1939 – 9 Oct 1958 (19 years, 221 days)

St John XXIII 28 October 1958 – 3 June 1963 (4 years, 218 days)

St Paul VI 21 June 1963 – 6 Aug 1978 (15 years, 46 days)

John Paul I 26 August 1978 – 28 Sep 1978 (33 days)

St John Paul II 16 October 1978 – 2 April 2005 (26 years, 168 days)

More Info: en.wikipedia.org