Cardinal Joseph Ratzinger, 78 - now to be known as Pope Benedict XVI - was the clear favourite to fill the vacancy left by John Paul II's death.
As one of the most influential men in the Vatican, he presided over the Pope's funeral earlier this month and was said to be among the pontiff's closest friends.
Cardinal Ratzinger has been head of the Congregation for the Doctrine of the Faith - formerly known as the Holy Office of the Inquisition - since 1981.