For more than two decades as prefect of the Congregation of the Doctrine of the Faith, Joseph Ratzinger was among Pope John Paul's key supporters in the effort to shore up faith around the world.
The German was widely discussed as a possible successor to John Paul. Observers say given his age of 78, Ratzinger might be considered a "transition" pope to follow John Paul's 26-year papacy. In his role as the guardian of church doctrine, Ratzinger silenced dissident theologians and repeated Church teachings. He draws support from conservatives who favor continuing John Paul's policies of barring women priests, abortion, euthanasia and contraception. Ratzinger became a cardinal in 1977.