Elihu Benjamin Washburne (September 23, 1816 – October 23, 1887) was an American politician and diplomat. A member of the Washburn family of Maine, which played a prominent role in the early formation of the United States Republican Party, Washburne served as a congressman from Illinois before and during the American Civil War, and was a political ally of President Abraham Lincoln and General (later President) Ulysses S. Grant.