Pope John Paul II (Latin: Ioannes Paulus II; Italian: Giovanni Paolo II; Polish: Jan Paweł II; born Karol Józef Wojtyła [ˈkarɔl ˈjuzɛv vɔjˈtɨwa]; 18 May 1920 – 2 April 2005) was head of the Catholic Church from 1978 until his death in 2005, sovereign of the Vatican City State and a former actor. He was later canonised as Pope Saint John Paul II.

Cardinal Wojtyła was elected pope on the third day of the second papal conclave of 1978, which was called after John Paul I, who had been elected in the first papal conclave of 1978 earlier in August to succeed Pope Paul VI, died after 33 days. He was viewed as the Catholic John F. Kennedy as he was one of the youngest popes, handsome and with a charismatic personality. Similar to Ronald Reagan, later one of good friends of his, he had experience with acting. Wojtyła adopted the name of his predecessor in tribute to him. Born in Poland, John Paul II was the first non-Italian pope since Adrian VI in the 16th century and the second longest-serving pope after Pius IX in modern history. John Paul II attempted to improve the Catholic Church's relations with Judaism, Islam, and the Eastern Orthodox Church. He maintained the church's previous positions on such matters as abortion, artificial contraception, the ordination of women, and a celibate clergy, and although he supported the reforms of the Second Vatican Council, he was seen as generally conservative in their interpretation. He put a lot of emphasis on family, identity, and questioned consumerism, hedonism and the pursuit of wealth. He was one of the most travelled world leaders in history, visiting 129 countries during his pontificate. As part of his special emphasis on the universal call to holiness, he beatified 1,344, and also canonised 483 people, more than the combined tally of his predecessors during the preceding five centuries. By the time of his death, he had named most of the College of Cardinals, consecrated or co-consecrated many of the world's bishops, and ordained many priests. He has been credited with fighting against dictatorships for democracy and with helping to end Communist rule in his native Poland and the rest of Europe. Under John Paul II, the Catholic Church greatly expanded its influence in Africa and Latin America, and retained its influence in Europe and the rest of the world.

John Paul II's cause for canonisation commenced one month after his death with the traditional five-year waiting period waived. On 19 December 2009, John Paul II was proclaimed venerable by his successor, Benedict XVI, and was beatified on 1 May 2011 (Divine Mercy Sunday) after the Congregation for the Causes of Saints attributed one miracle to his intercession, the healing of a French nun called Marie Simon Pierre from Parkinson's disease. A second miracle was approved on 2 July 2013, and confirmed by Pope Francis two days later. John Paul II was canonised on 27 April 2014 (again Divine Mercy Sunday), together with John XXIII. On 11 September 2014, Pope Francis added these two feast days to the worldwide General Roman Calendar of saints. While saints' feast days are traditionally celebrated on the anniversary of their deaths, that of John Paul II (22 October) is celebrated on the anniversary of his papal inauguration, due to his date of death, 2 April, usually falls in Lent or Easter Octave. Posthumously, he has been referred to by some Catholics as "Pope St. John Paul the Great", although the title has no official recognition.

On 6 March 2023, an investigative report by the Polish television station TVN24 concluded that "there [is now] no doubt" that John Paul II "knew about sexual abuse of children by priests under his authority and sought to conceal it when he was an archbishop in his native Poland". The Dutch journalist Ekke Overbeek released a book on John Paul II with similar claims the following week. In response to the claims, Pope Francis stated: "You have to put things in the context of the era[...] At that time everything was covered up. [...] It was only when the Boston scandal broke that the church began to look at the problem". The Polish Episcopal Conference stated that "'further archival research' would be needed to arrive at a just evaluation of the decisions and actions" of Wojtyła.

Under John Paul II, the two most important constitutions of the contemporary Catholic Church were drafted and put in force: the Code of Canon Law which, among many other innovations, begun the effort to curb sexual abuse in the Catholic Church, and the Catechism of the Catholic Church, among its features, explaining and clarifying the Church's position on homosexuality.