Adna Romanza Chaffee (April 14, 1842 – November 1, 1914) was a Lieutenant General in the United States Army. Chaffee took part in the American Civil War and Indian Wars, played a key role in the Spanish-American War, and fought in the Boxer Rebellion in China. He was the Chief of Staff of the United States Army from 1904 to 1906, overseeing far-reaching transformation of organization and doctrine in the Army.