Kofi Annan, a soft-spoken and patrician diplomat from Ghana, who became the seventh secretary general of the United Nations, projecting himself and his organization as the world’s conscience and moral arbiter despite bloody debacles that left indelible stains on his record as a peacekeeper, died on Saturday. He was 80.

His death, after a short illness, was confirmed by his family in a statement from the Kofi Annan Foundation, which is based in Switzerland.

Awarded the Nobel Peace Prize in 2001, he was the first black African to head the United Nations, and led the organization for two successive five-year terms beginning in 1997 — a decade of turmoil that challenged the sprawling body and redefined its place in a changing world.

On his watch as what the Nobel committee called Africa’s foremost diplomat, Al Qaeda struck New York and Washington, the United States invaded Iraq, and Western policymakers turned their sights from the Cold War to globalization and the struggle with Islamic militancy.