Kofi Annan, former UN Secretary-General, died early on Saturday morning due to an "undisclosed illness," Reuters reports. He was 80 years old.

The big picture: UN Secretary-General António Guterres said Annan "was the United Nations. He rose through the ranks to lead the organization into the new millennium with matchless dignity and determination." He was the first black African to lead the UN, CNN reports, and passed away "peacefully" with his family at his side.

Annan received the Nobel Peace Prize in 2001 along with the UN for efforts to "give priority to human rights issues," Reuters reports.

• He was criticized during his tenure for the UN's failure to stop the Rwanda genocide.
• He said of the UN last year: "The UN can be improved, it is not perfect but if it didn't exist you would have to create it."
• Former President Barack Obama said in a statement: "Kofi Annan was a diplomat and humanitarian who embodied the mission of the United Nations like few others. His integrity, persistence, optimism, and sense of our common humanity always informed his outreach to the community of nations. ... Michelle and I offer our condolences to his family and many loved ones."