Kofi Annan, who died Saturday at the age of 80, led the United Nations through the divisive years of the Iraq war and the trauma of the September 11, 2001 attacks.
The first secretary-general from sub-Saharan Africa, Ghanaian-born Annan was credited for raising the UN's profile during his two-term tenure, from January 1997 to December 2006.
The charismatic, quiet-spoken career diplomat will be remembered as the United Nations' star secretary-general - and arguably the world body's most popular leader.
But, as peacekeeping chief, two of the UN's darkest chapters - the Rwandan genocide and the Bosnian war - happened on his watch.
"I have sought to place human beings at the center of everything we do - from conflict prevention to development, to human rights," Annan said in his 2001 speech after accepting the Nobel Peace Prize.
At the time, as the world was reeling from the September 11 attacks, Annan and the organisation were jointly given the honor "for their work for a better organised and more peaceful world."
Promoted from within
Annan - the seventh secretary-general - devoted four decades of his working life to the United Nations and was the first chief to rise from within the organisation's ranks.
After heading up UN human resources and then its budget office, he was appointed peacekeeping chief in 1993, a post he held until he was catapulted to the top UN job four years later.
In recent years, Annan had returned to the diplomatic stage to lead an advisory commission in Myanmar on the crisis in Rakhine state.
He had encouraged the government to grant citizenship to the Muslim Rohingya. More than 700,000 Rohingya were driven out of Rakhine in an army campaign last year.
He also set up a foundation devoted to conflict resolution and joined the Elders group of statesmen, which regularly speaks out on global issues.
In his autobiography "Interventions: A Life in War and Peace," Annan wrote that he envisioned the United Nations as serving "not only states but also peoples" as "the forum where governments are held accountable for their behavior toward their own citizens."
The UN's failures to live up to that promise in Rwanda and Bosnia would shape Annan's tenure as secretary-general, he wrote.
The blue helmets pulled out of Rwanda in 1994 during the bloody chaos and a year later, the world body failed to protect its own "safe area" of Srebrenica when Bosnian Serb forces rounded up and killed thousands of Muslim men and boys.
Those debacles "left me with what would become my greatest challenge as secretary-general: creating a new understanding of the legitimacy, and necessity, of intervention in the face of gross violations of human rights," Annan wrote.
'Diplomatic rock star'
While Rwanda and Srebrenica cast a pall over his tenure as peacekeeping chief, Annan transitioned into his new role as UN chief with ease.
He quickly became a familiar face on television, his name made newspaper headlines, and he was a sought-after guest at gala events and New York dinner parties.
He was often described as a "diplomatic rock star."
Annan owed his appointment to the United States, which had vetoed a second term for Egypt's Boutros Boutros-Ghali after relations went sour, but he often proved his independence from major powers.
He annoyed the United States when he said the 2003 invasion of Iraq was "illegal" because it was not endorsed by the UN Security Council.
Annan was later accused of corruption in the Iraq oil-for-food scandal, one of the most trying times of his tenure.
Some commentators saw the 2005 investigation of Annan and his son as payback for his invasion comments.
A commission on inquiry cleared Annan of any serious wrongdoing, but found ethical and management lapses linked to his son Kojo's ties with a Swiss firm that won lucrative contracts under the scheme.
Annan later admitted that the scandal had sorely tested his mettle not only as secretary-general, but as a father.
From Ghana to Geneva
Born in Kumasi, the capital city of Ghana's Ashanti region, Annan was the son of an executive of a European trading company, the United Africa company, a subsidiary of the Anglo-Dutch multinational Unilever.
In his autobiography, he describes coming of age along with the independence movement in Ghana, and experiencing a "complete change in culture and society."
He attended a Methodist-founded boarding school at the age of 13 and went to university in Kumasi before receiving a scholarship to study in the United States.
He studied economics at Macalester College in Minnesota and management at the Massachusetts Institute of Technology.
He also attended the Graduate Institute of International and Development Studies in Geneva.
In 1965, Annan married Titi Alakija, a Nigerian woman from a well-to-do family. They had a daughter, Ama, and Kojo, but the couple separated in the late 1970s.
He was married a second time in 1984 to Nane Lagergren, a Swedish lawyer at the United Nations and the niece of Raoul Wallenberg. They have a daughter, Nina.
After ending his second term as UN chief, Annan went on to take high-profile mediation roles in Kenya and in Syria.
He enjoyed some success in ending post-election turmoil in Kenya in 2007, but he resigned from a peace mission for Syria.
Annan complained that divisions among world powers at the Security Council had turned his job as Syria envoy into a "mission impossible."