Henry Walton Grinnell (November 19, 1843 – September 2, 1920), known as Walton Grinnell, was a naval veteran of the American Civil War and the Spanish–American War. He became a rear admiral and Inspector-General in the Imperial Japanese Navy and served at the battle of the Yalu River in the Sino-Japanese War of 1894–95. He was discharged as an admiral at the end of the war.