Brian Andrew Nichols is an American diplomat serving as Assistant Secretary of State for Western Hemisphere Affairs. He previously served as the United States Ambassador to Peru from 2014 until 2017, as well as the U.S. Ambassador to Zimbabwe from 2018 until 2021.

The Assistant Secretary of State for Western Hemisphere Affairs is the head of the Bureau of Western Hemisphere Affairs within the United States Department of State, the foreign affairs department of the United States federal government. The Assistant Secretary of State guides operation of the U.S. diplomatic establishment in the countries of the Western Hemisphere and advises the Secretary of State and the Under Secretary for Political Affairs.