In February 2012, Mr. Annan was appointed as the joint envoy of the Arab League and the United Nations to seek a settlement as civil war tightened its grip on Syria. But he resigned in frustration in August of that year, citing the intransigence of both sides in a conflict that convulsed and reshaped the region and claimed hundreds of thousands of lives.

Kofi Atta Annan was born on April 8, 1938, in the city of Kumasi in what was then Gold Coast and which, in 1957, became Ghana, the first African state to achieve independence from British colonialism. Born into an aristocratic family, he had three sisters, two of them older. The third, Efua, was a twin who died in the 1990s.

After a spell at the elite Mfantsipim boarding school founded by Methodists, he went on to higher education as an economist in Ghana, at Macalester College in St. Paul, in Geneva, and at the M.I.T. Sloan School of Management.

In 1965, he married Titi Alakija, a woman from a prosperous Nigerian family. The couple had two children, a daughter, Ama, and a son, Kojo. The marriage foundered in the late 1970s.

In 1984, Mr. Annan married Ms. Lagergren, a divorced lawyer working at the United Nations. She, too, was a scion of a prominent family, a niece of Raoul Wallenberg, the Swedish diplomat who protected thousands of Hungarian Jews during World War II but disappeared after being captured by Soviet forces. Ms. Lagergren had a daughter, Nina, from her first marriage.

He is survived by Ms. Lagergren, along with Ama, Kojo and Nina.

Most of Mr. Annan’s working life was spent in the corridors and conference rooms of the United Nations, but, he told the author Philip Gourevitch in 2003, “I feel profoundly African, my roots are deeply African, and the things I was taught as a child are very important to me.”

His first appointment with a United Nations agency was in 1962, at the World Health Organization in Geneva. Mr. Annan returned briefly to Ghana to promote tourism and worked in Ethiopia with the U.N. Economic Commission for Africa before returning to the body’s European headquarters.