He visited 116 countries, promoting church teaching on personal behavior and public morality and condemning what he said was a decline of spiritual values brought about by the rising materialism of the twentieth century. The most traveled pope in history was also the first non-Italian to lead the church in more than four and a-half centuries.
He died in his Vatican apartment on Saturday.
Born in Poland, he secretly trained for the priesthood under Nazi occupation, lived under Communism, and contributed to the fall of the Iron Curtain by denouncing the oppression of Christians.
John Paul II unequivocally opposed pre- and extra-marital sex, homosexuality, abortion, and the use of contraception.
His opposition to the ordination of women as priests was a major point of contention for many liberal Catholics, as was the Vatican's slow response under his leadership to sex scandals around the world, especially in the United States.
At the same time he won praise, especially but not exclusively among conservatives, for his unwavering position that Catholic beliefs - for example on the sanctity of life - are not subject to popular opinion.
John Paul was the first pope to publicly ask forgiveness for the Church's past sins - including mistreatment of Jews and other non-believers.
"For the role that each one of us has had, with his behavior, in these evils, contributing to a disfigurement of the face of the Church, we humbly ask forgiveness," said the pontiff on the altar at St. Peter's five years ago, in remarks some hailed as a landmark but others thought fell short of the mark in not specifically mentioning the Holocaust.
Elected to the papacy in October 1978, an energetic figure at age 58, John Paul II was welcomed by Catholics who thought the first non-Italian pope in over 450 years might also be the one whose papacy would usher in a more open era in the Church.
He was the most visible of popes, hitting the road soon after choosing his name - in memory of 20th century pontiffs Paul VI and John XXIII - the latter particularly and deliberately evocative, as John XXIII was the one to usher in dramatic reforms involving ordinary Catholics in the affairs of the Church.
Among his travels, in 1998 he made a highly publicized visit to Cuba, during which he helped to negotiate the release of 300 political prisoners.
A priest nearly all his adult life, John Paul had a remarkably varied resume. As a young man, he worked in a quarry for a chemical company and was a playwright and actor accustomed to rehearsing in secret, to avoid reprisals from Nazi security police.
A pope who had been a manual laborer was a change of pace for the Catholic Church, as was his love of soccer, swimming, canoeing and skiing, pastimes shelved as he stepped into the limelight at the Vatican, but characteristics which endeared him to many, making him seem more like a man of the people.
The future pontiff's studies for the priesthood were done underground, because of the German occupation, and some of his fellow students were carted off to firing squads or sent to concentration camps.