Pope Benedict XVI will resign at the end of February due to his age and diminishing strength.
The German-born Pontiff, 85, was elected to the Papacy in 2005, only the second non-Italian Pope since 1522 and the oldest on election since the 18th century.
As the powerful Cardinal Joseph Ratzinger, he was already well-known within the Catholic world before his election to the top job.
His image on elevation to the Papacy was one of an enforcer of Catholic orthodoxy and a cerebral disciplinarian who was unafraid to crack down on liberals and dissidents within the church, he gained the nickname "God's Rottweiler".
His pronouncements before becoming Pope included labelling homosexuality a "more or less strong tendency ordered toward an intrinsic moral evil" and saying rock music could be a "vehicle of anti-religion".
Since his election as Pontiff his image has softened, leading him to be dubbed "Benedict the Benign", but he still did court controversy.
Perhaps his biggest setback as Pope was during his visit to Germany in 2006 when he was caught in a firestorm of criticism from the Islamic world after giving a lecture at his old university of Regensburg.
Quoting from an obscure Medieval text, he cited the words of a Byzantine emperor who characterised some of the teachings of the Prophet Mohammed, Islam's founder, as "evil and inhuman" - remarks that touched off widespread anger across the Muslim world.
The anger and violence sparked by his comments including attacks on seven churches in the West Bank and Gaza posed one of the biggest international crises involving the Vatican in decades.
He later apologised, saying he was "deeply sorry" about the angry reaction to his remarks about Islam and holy war, saying the text he quoted did not reflect his personal opinion.
The last pope to resign was Pope Gregory XII, who stepped down in 1415.
The Vatican hope to have the Pope's successor in place by the end of March.