Joseph Ratzinger was born and raised in Germany, where he briefly served in the Hitler Youth, despite his objections, and the German military during World War II. He then established himself as a leading theologian, professor and local Catholic leader before rising up the Vatican ranks.
He was dean of the College of Cardinals in 2005 when he became the sixth German to be picked as pope, albeit the first since the 11th century. At the time, the church was facing several pressing issues, including declining popularity in parts of the world and a growing crisis over the church's role in handling molestation accusations against priests around the world.
Given his age at the time -- 78 -- he was widely seen as a caretaker pope, a bridge to the next generation after the long tenure of John Paul II, a popular, globe-trotting pontiff whose early youth and vigor gave way to such frailty in later years that he required help walking and was often hard to hear during public addresses.
As an aide to John Paul, Benedict served as a strict enforcer of his conservative social doctrine. To no one's surprise, he continued to espouse a conservative doctrine after taking the office himself. He frequently warned of a "dictatorship of relativism."
"In a world which he considered relativist and secular and so on, his main thrust was to re-establish a sense of Catholic identity for Catholics themselves," said Delia Gallagher, contributing editor for Inside the Vatican magazine.
Not everyone embraced this conservatism. CNN iReporter Egberto Willies, a former Catholic, said positions such as opposing the distribution of condoms to curb the AIDS epidemic in Africa shows how "outdated" the church under Benedict was.
"This is a pope that was so conservative that many of his values simply, in today's world, made no sense," said Willies, a resident of Kingwood, Texas.
Bill Donohue, of the conservative U.S. Catholic League, credited Benedict for working to reduce friction among adherents of various faiths, something that was a key part of John Paul's mission as well.
"The pope made it clear that religious freedom was not only a God-given right, it was 'the path to peace,'" Donohue said.
But Mohammed Shafiq, chief executive of the Ramadhan Foundation, offered a different take. He referenced a 2006 speech Benedict made in which he quoted from 14th century Byzantine emperor Manuel II Paleologus saying the Muslim Prophet Mohammed brought into the world "things only evil and inhuman." These remarks spurred protests by Muslims worldwide and an apology from the pope.
"This sadly meant the hard work of his predecessor Pope John Paul II was tarnished and required extensive work to rebuild ties between Christianity and Islam," Shafiq said. "That is something he has tried to do over the past eight years, and we do wish it could have started better than it did."
In his tone, demeanor and actions, Benedict was notably different from his predecessor. Where John Paul wowed crowds around the world with his mastery of numerous languages, Benedict's influence will be felt through his writings, part of his training as a college professor, Gallagher said.
Allen called Benedict a "great teaching pope."
Praised, criticized for actions regarding sex abuse
Benedict became pope at the height of the molestation scandal involving Catholic priests, with complaints of sexual abuse and lawsuits over the issue tearing at the church and threatening its moral standing around the world.
In 2008, he acknowledged "the shame which we have all felt" over abuse reports and said those responsible for the "evils" should face justice. Two years later in 2010 -- the same year that he issued new rules aimed at stopping abuse -- he said abusive priests "disfigured their ministry" and brought "profound shame and regret" on the church.
The new rules included allowing church prosecution of suspected molesters for 20 years after the incidents occurred, up from 10 years previously. The rules also made it a church crime to download child pornography and allowed the pope to remove a priest without a formal Vatican trial.
"No one did more to successfully address the problem of priestly sexual abuse than Joseph Ratzinger," Donohue said.
But others -- such as Barbara Blaine, president of Survivors Network of those Abused by Priests -- say the opposite is true.