William Huie Duncan[1] is an American diplomat who has served as the United States ambassador to El Salvador since February 2023.

[2] Before joining the Foreign Service in 1992, he served as a commissioned officer in the United States Navy and as an attorney with the U.S. Environmental Protection Agency.

[5] He has also served other missions in Asunción, Madrid, Baghdad, Mexico City, Bogotá, San Salvador, and Matamoros.

[2] On February 25, 2022, President Joe Biden nominated Duncan to be the next United States Ambassador to El Salvador.

[7] He was sworn in by Assistant Secretary Brian A. Nichols on January 24, 2023,[8] and he presented his credentials to President Nayib Bukele on February 2, 2023.