Hassan Rowhani, the cleric who won Iran's presidential election on Saturday, is a moderate who has pledged to engage more with world powers in hopes of easing crippling economic sanctions.
Rowhani headed Iran's nuclear negotiating team in the early 2000s under reformist president Mohammad Khatami.
He has been an outspoken critic of outgoing President Mahmoud Ahmadinejad, accusing him of needlessly antagonising the international community.
The 64-year-old has said there will be "no surrender" to Western demands in talks on Iran's controversial nuclear programme but has promised a more constructive and less adventurist approach.
Rowhani was the lone cleric among the six candidates approved to stand in Friday's election.
He benefited from the withdrawal of the only other moderate in an original field of eight -- Khatami's reformist first vice president Mohammad Reza Aref.
That and endorsement by both Khatami and his moderate conservative predecessor Akbar Hashemi Rafsanjani enabled Rowhani to win the votes of reformists and moderates alike, even though he is a member of the conservative Association of Combatant Clergy.
Despite winning the endorsement of key reformers, he was careful in campaigning to keep his distance from the reformist standardbearers of the 2009 presidential election, both of whom remain under house arrest after claims of fraud sparked months of mass protests.
When pictures of one of them, former prime minister Mir Hossein Mousavi, were displayed at one of his rallies and prompting several arrests, his campaign put out a statement condemning "any improper action" and asking everyone to respect the law.
A committed supporter of the founder of the Islamic republic, Ayatollah Ruhollah Khomeini, even before the 1979 revolution, Rowhani has held a succession of leading posts.
He was a member of parliament from 1980 to 2000, when he became a member of the Assembly of Experts, the body that supervises the work of supreme leader Ayatollah Ali Khamenei.
From 1989 to 2005, he served as secretary of the supreme national security council, Iran's top security post, and remains a council member.
He prides himself on maintaining good relations with Khamenei, who has the final say in all strategic matters, including nuclear policy.
As nuclear negotiator from 2003 to 2005, Rowhani oversaw a moratorium on uranium enrichment, the process at the heart of Western concerns over Iran's ambitions. That won him the respect of his European interlocutors and the monicker "diplomat sheikh".
But the policy, which was abandoned after he quit, earned him the derision of hardliners who accused him of "falling under the spell of the tie and after-shave" of then British foreign minister Jack Straw.
Rowhani chose a key as his campaign symbol, telling a campaign rally: "This is the key to solving Iran's problems."
"I have come forward to save Iran's economy and forge a constructive interaction with the world through a government of wisdom and hope," he said in announcing his candidacy.
"This administration made fun of sanctions, deriding them as scrap paper, while we could have avoided them or to some extent reduced them."
EU and US sanctions that have bitten over the past two years have sent inflation soaring to more than 30 percent as the rial has lost nearly 70 percent of its value against the dollar.
Rowhani has vowed to restore diplomatic ties with arch-foe the United States, which severed relations in the aftermath of the 1979 seizure of the US embassy by Islamist students.
He has also pledged that "discrimination against women will not be tolerated" under his administration.
Married with four children, Rowhani holds a doctorate in law from Scotland's Glasgow Caledonian University, according to his official CV.
He was born in 1948 in the town of Sorkheh, near Semnan, southeast of Tehran.