Ebrahim Raisi, the hardline judiciary chief, has been a fixture of Iranian politics for decades and is well-known in Iran and globally for his role in the execution of thousands of prisoners in the 1980s.
Mr Raisi was the preferred candidate of Supreme Leader Ayatollah Ali Khamenei, who is said to consider Mr Raisi a close confidant and possible successor. Many believe his win was predetermined and a stepping stone to his eventual role as Supreme Leader.
He won the presidential elections with 17.8 million votes, out of 28.6 million cast, to succeed reformist Hassan Rouhani who had spent eight years in his post.
Through the election period, Mr Raisi seemed to tone down his normally extreme anti-West hardline rhetoric, suggesting he would continue negotiations with the US and Europe on a new nuclear deal as a way to relieve sanctions pressure.
He also spent much of his campaigning focused on Iran's economic issues, pledging to tackle “poverty and corruption, humiliation and discrimination.”
Mr Raisi was born in 1960 in a small village near the holy city of Mashhad. As a teenager, he went to Qom to enter a seminary, where he studied under Mr Khamenei. While in Qom he became politically active, participating in protests against the shah prior to the revolution.
During the early years of the Islamic Republic, Mr Raisi began his judicial career. He was appointed prosecutor of Karaj and subsequently deputy prosecutor in Tehran.
Following the end of the Iran-Iraq war in 1988, then-Supreme Leader Ruhollah Khomeini appointed Mr Raisi to a “death commission” that led to the mass execution of political dissidents.
Amnesty International says more than 5,000 prisoners, most of them connected to the anti-regime People's Mujahideen, were killed. Mr Raisi's role in the executions has been condemned by human rights groups around the world. The Centre for Human Rights in Iran has called on the International Criminal Court to investigate him over alleged crimes against humanity.
In 2009, Mr Raisi defended the executions of more than a dozen people who took part in the Green Revolution protests that followed former President Mahmoud Ahmadinejad's re-election.
In 2016, Mr Khamenei appointed him as custodian of Astan Quds Razavi, the foundation that manages the shrine of Imam Reza in Mashhad, Mr Raisi's home city.
Mr Raisi ran for president in 2017, collecting 16 million votes but losing to President Rouhani in a landslide win for the moderate candidate.
In 2019, He was named head of Iran’s judiciary by Mr Khamenei as well as deputy chief of the Assembly of Experts, the clerical group that selects the Supreme Leader. His two years as chief justice have been marked by human rights abuses and the increasing repression of any kind of dissent in Iran. He has overseen the execution of a number of Iranians who have participated in political protest, including a champion wrestler.
In November 2019, the Trump administration imposed sanctions on Mr Raisi and other members of the supreme leader’s inner circle for “advancing the regime’s domestic and foreign oppression,” which included the execution of minors.
With Mr Raisi now at the helm of the country, many believe Iran is about to face one of its most repressive presidencies. Analysts expect that many of the freedoms ushered in by the moderate Rouhani administration are likely to be reversed in favour of conservative values and hardline policies.