Who will be the next pope? The decision could have a profound impact on the Catholic Church and the world's 1.4 billion baptised Roman Catholics.
It also promises to be a highly unpredictable and open process for a host of reasons.t
The College of Cardinals will meet in conclave in the Sistine Chapel to debate and then vote for their preferred candidates until a single name prevails.
With 80% of the cardinals appointed by Pope Francis himself, they are not only electing a pope for the first time, but will offer a broad global perspective.
For the first time in history, fewer than half of those given a vote will be European.
And although the college may be dominated by his appointments, they were not exclusively "progressive" or "traditionalist".
For those reasons, it is harder than ever to predict who will be elected the next Pope.
Could the cardinals elect an African or an Asian Pope, or might they favour one of the old hands of the Vatican administration?
Here is a selection of names being mentioned as Francis's potential successor, and we expect more to emerge in the coming days.
Pietro Parolin
Nationality: Italian
Age: 70
Softly spoken Italian Cardinal Parolin was the Vatican's secretary of state under Pope Francis – making him the Pope's chief adviser. The secretary of state also heads the Roman Curia, the Church's central administration.
Having acted effectively as deputy pope, he could be considered a frontrunner.
He is viewed by some as more likely to prioritise diplomacy and a global outlook than the purity of Catholic dogma. His critics consider that a problem, while his supporters see a strength.
But he has been critical of the legalisation of same-sex marriage around the world, calling a landmark 2015 vote in favourin the Republic of Ireland "a defeat for humanity".
The bookmakers may back him but Cardinal Parolin will be well aware of an old Italian saying that stresses the uncertainty of the pope-picking process: "He who enters a conclave as a pope, leaves it as a cardinal."
Some 213 of the previous 266 popes have been Italian and even though there has not been an Italian pope in 40 years, the pivot of the upper echelons of the Church away from Italy and Europe may mean there may not be another for now.
Luis Antonio Gokim Tagle
Nationality: Filipino
Age: 67
Could the next pope come from Asia?
Cardinal Tagle has decades of pastoral experience – meaning he has been an active Church leader among the people as opposed to a diplomat for the Vatican or cloistered expert on Church law.
The Church is massively influential in the Philippines, where about 80% of the population is Catholic. The country currently has a record five members of the College of Cardinals – which could make for a significant lobbying faction if they all back Cardinal Tagle.
He is considered a moderate within the Catholic definition, and has been dubbed the "Asian Francis" because of a dedication to social issues and sympathy for migrants that he shared with the late pope.
He has opposed abortion rights, calling them "a form of murder" – a position in line with the Church's broader stance that life begins at conception. He has also spoken against euthanasia.
But in 2015 when he was Archbishop of Manila, Cardinal Tagle called for the Church to reassess its "severe" stance towards gay people, divorcees and single mothers, saying past harshness had done lasting harm and left people feeling "branded", and that each individual deserved compassion and respect.
The cardinal was considered a candidate to be pope as far back as the 2013 conclave in which Francis was elected.
Asked a decade ago how he viewed suggestions he could be next, he replied: "I treat it like a joke! It's funny."
Fridolin Ambongo Besungu
Nationality: Congolese
Age: 65
It's very possible the next Pope could be from Africa, where the Catholic Church continues to add millions of members. Cardinal Ambongo is a leading candidate, hailing from the Democratic Republic of Congo (DRC).
He has been Archbishop of Kinshasa for seven years, and was appointed cardinal by Pope Francis.
He is a cultural conservative, opposing blessings for same-sex marriage, stating that "unions of persons of the same sex are considered contradictory to cultural norms and intrinsically evil".
Though Christianity is the majority religion in the DRC, Christians there have faced death and persecution at the hands of jihadist group Islamic State and associated rebels. Against that backdrop, Cardinal Ambongo is viewed as a fierce advocate for the Church.
But in a 2020 interview, he spoke in favour of religious plurality, saying: "Let Protestants be Protestants and Muslims be Muslims. We are going to work with them. But everyone has to keep their own identity."
Such comments could lead some cardinals to wonder if he fully embraces their sense of mission - in which Catholics hope to spread the Church's word throughout the world.
Peter Kodwo Appiah Turkson
Nationality: Ghanaian
Age: 76
If chosen by his peers, the influential Cardinal Turkson would likewise have the distinction of being the first African pope for 1,500 years.
Like Cardinal Ambongo, he has claimed not to want the job. "I'm not sure whether anyone does aspire to become a Pope," he told the BBC in 2013.
Asked if Africa had a good case to provide the next Pope based on the Church's growth on the continent, he said he felt the Pope shouldn't be chosen based on statistics, because "those types of considerations tend to muddy the waters".
He was the first Ghanaian to be made a cardinal, back in 2003 under Pope John Paul II.
Like Cardinal Tagle, Cardinal Turkson was considered a potential Pope a decade later, when Francis was chosen. In fact, bookmakers made him the favourite ahead of voting.
A guitarist who once played in a funk band, Cardinal Turkson is known for his energetic presence.
Like many cardinals from Africa, he leans conservative. However, he has opposed the criminalisation of gay relationships in African countries including his native Ghana.
In a BBC interview in 2023, while Ghana's parliament was discussing a bill imposing harsh penalties on LGBTQ+ people, Turkson said he felt homosexuality should not be treated as an offence.
Back in 2012, he was accused of making fear-mongering predictions over the spread of Islam in Europe at a Vatican conference of bishops, for which he later apologised.
