There is no interim pope. However, upon the death or resignation of a pope the camarlengo acts as a temporary administrator until the new pope is elected. He has no power to make major decisions and primarily arranges the papal funeral as well as preparations for the upcoming conclave. In the case of Pope Benedict XVI that was Cardinal Tarcisio Pietro Evasio Bertone.
The camarlengo assumes leadership in the absence of a pope. He has no power to make any changes to the Church and his primary responsibilities would be to arrange for the funeral of the previous pope and set up the conclave to elect a new pope.
The cardinals frequently select one of the older and more experienced members of the college to be pope. However, when Pope John Paul II was elected he was only 58 years old. Sometimes, if they are having problems choosing a pope, they might compromise and choose an 'interim' pope, one of their oldest members who will probably serve only a short time hoping that one or two popular leaders emerge during the interim pope's reign.
.Catholic AnswerPope John XXIII preceded Pope Paul VI. Pope John XXIII was elected when Pope Pius XII died. They really didn't think he was going to be Pope very long, or do anything much. He called and opened the Second Vatican Council. So much for "interim" popes who don't accomplish much, the Lord works in mysterious ways. See the Vatican article on Pope John XXIII, he was a very nice man, I remember reading his diary, he was also a very holy man.
Pope Paul VI was elected pope after the death of Pope John XXIII.
John Paul II
There is no pope named Pope XXIII. If you are referring to Pope John XXIII, he became pope in 1958.
Pope Francis is the reigning pope in 2013.
The current pope is Pope Benedict XVI.
Pope Pius III was the predecessor of Pope Julius II.
Pope Benedict followed Pope John Paul II as pope.
It was Pius XII. He was pope from Mar. 2, 1939 to his death on Oct. 9, 1958.
12 popes have taken the name "Pius". Some of them were also canonized as saints. Pope Pius I, saint, Pope 140/142 to 155 Pope Pius II, Pope 1458 to 1474 Pope Pius III, Pope in 1503 Pope Pius IV, Pope 1559 to 1565 Pope Pius V, saint, Pope 1566 to 1572 Pope Pius VI, Pope 1775 to 1799 Pope Pius VII, Pope 1800 to 1823 Pope Pius VIII, Pope 1829 to 1830 Pope Pius IX, Pope 1846 to 1878 Pope Pius X, saint, Pope 1903 to 1914 Pope Pius XI, Pope 1922 to 1939 Pope Pius XII, Pope 1939 to 1958