William Graham Walker (born June 1, 1935) is a veteran United States Foreign Service diplomat who served as the US ambassador to El Salvador and as the head of the Kosovo Verification Mission.
Walker was born in Kearny, New Jersey, and has served mostly in Latin America, notably Bolivia, Brazil, El Salvador, Honduras, Peru, and on the Argentina desk at the US State Department.
From 1985-1988, he served as Deputy Assistant Secretary of State in the Bureau of Inter-American Affairs, with responsibility for relations with Central America and Panama. By coincidence, he shares his name with a historical soldier of fortune who in the 19th century attempted to conquer parts of Central America (and was ultimately executed). From 1988-1992, he served as Ambassador to El Salvador. He was the Vice President of the National Defense University in Washington, D.C. between 1994-1997.
In August 1997, Walker was named as a Special Representative of the Secretary General and was appointed to head the United Nations Transitional Administration for Eastern Slavonia, Baranja and Western Sirmium (UNTAES). He led a mission consisting of some 800 UN civilian and 2,500 military peacekeepers and administrators. The mission was responsible for overseeing the peaceful reintegration of this Serb-controlled region of eastern Slavonia into Croatia following the end of the Croatian War.