William Ira Cargo (February 27, 1917 – December 13, 2005) was an American diplomat and foreign policy advisor who served as the United States Ambassador to Nepal from 1973 to 1976.

He earned a Bachelor of Arts degree from Albion College and a PhD in political science from University of Michigan.

As a graduate student, Cargo also contributed to articles published in the American Political Science Review.

Cargo worked in the Office of Dependent Area Affairs and was selected to attend the National War College in 1953 and 1954.

He later served as Deputy U.S. Representative to the International Atomic Energy Agency and was assigned to the U.S. embassy in Pakistan.