Adored by some, attacked by others, Pope John Paul is perhaps the most widely recognized person in the world.
On the world stage, he has been at once a champion of the downtrodden and an often contested defender of orthodoxy within his own church of a billion members.
In recent months, the world has watched the swift decline in the health of the 83-year-old pope, who suffers from Parkinson's disease and severe arthritis. He has been unable to complete his prepared speeches and has difficulty pronouncing his words.
His iron will to keep going should be on full display on Thursday when he celebrates his 25th anniversary as pope with a gruelling schedule of masses and meetings followed by the beatification of Mother Teresa on Sunday and the induction of 31 new cardinals the following Tuesday.
The Polish pope burst on the scene on October 16, 1978, when cardinals in a secret conclave chose him as the first non-Italian pontiff in four and a half centuries.
Now the fourth longest-serving pope in Roman Catholic history, the steely-willed John Paul won a bet with fate three years ago and ushered his church into the new millennium despite his sapped stamina.
Historians say one of the pope's most lasting legacies will be his role in the fall of communism in Eastern Europe in 1989.
Poles believe his unflagging support for the banned Solidarity trade union while communists tried to crush it was a potent force keeping the movement alive.
Solidarity formed the East Bloc's first non-communist government in 1989, marking the start of a wave of freedom which saw Marxist regimes fall like dominoes across Europe.
"Behold the night is over, day has dawned anew," the pope said during a triumphant visit to Czechoslovakia in 1990.
A decade after witnessing the fall of communism he fulfilled another of his dreams. He visited the Holy Land in March 2000, and, praying at Jerusalem's Western Wall, he asked forgiveness for Catholic sins against Jews over the centuries.
A GLOBAL PULPIT
A tireless traveler who clocked up some 1.25 million kilometers (775,000 miles) in 102 foreign trips to some 130 countries, the pope is a familiar figure across the globe. He has drawn crowds of up to four million people.
He has been determined to use his office to draw attention to the plight of the world's neediest and oppressed while at the same time keeping a firm and conservative grip on his Church.
"I speak in the name of those who have no voice," he said on a trip to Africa in 1980.
For the pope, those with no voice could mean the unborn child or the dissident rotting in jail.
He has felt just as much at ease lecturing dictators of the left and the right as he has telling leaders of world democracies that unbridled capitalism and globalization are no panacea to the world's post-Cold War problems.
A strong defender of human rights and religious freedom, his calls for a "new world economic order" and defense of workers' rights have led some to call him "the Socialist pope."
An untiring advocate of peace and nuclear disarmament, he has often warned that mankind was heading for Armageddon and in 2003 led the Vatican's campaign against the war in Iraq.
A former actor who wrote several plays, Pope John Paul has used his mastery of timing, levity and languages to communicate like few other world figures of modern times.
CHRISTIAN UNITY
He is the first pope to preach in a Protestant Church and a synagogue, the first pope to set foot inside a mosque and has been an untiring advocate of Christian unity.
But ironically, over in the past 25 years he also has been a visible source of deep division to his own church.
Many Catholics, particularly in developed countries, have disregarded his teachings against contraception, contested his ban on women priests and campaigned for a liberal successor.
John Paul has not been swayed by their protests. Concerned that many Catholics have strayed from traditional teachings, he has waged an unflagging battle against abortion, contraception, pre-marital sex, divorce, homosexuality and the breakdown of traditional family values.
From Haiti to the United States, from Brazil to Austria, he has revived conservative Catholic self-awareness and stressed obedience to the Church's hierarchy in the midst of dissent.
Liberal theologians balked, signing petitions accusing him of wielding too much power. But he once told reporters: "Church doctrine cannot be based on popular opinion."
He has appointed more than 95 percent of cardinals who could enter a conclave to elect his successor, thus stacking the odds the next pope will not tamper with his controversial teachings.
Karol Wojtyla was born on May 18, 1920 in the small town of Wadowice, near Krakow, in a humble apartment house. His father was a non-commissioned officer in the Polish army and his mother died in 1929 when he was eight.
In 1938, Karol moved to Krakow, where he entered the Jagellonian University. The Nazis closed the university when they invaded in 1939, and to escape death or deportation the students merged with the population, becoming laborers.
But he studied for the priesthood secretly during the occupation and was ordained a priest after the war in 1946.
He was made archbishop of Krakow in 1963 and promoted to cardinal in 1967, becoming one of Poland's leading anti-communist churchmen during the post-war period.
After the early death of John Paul I, Wojtyla became the 264th successor of St Peter and, at 58, the youngest Pope for more than a century.