Spencer Oliver Fisher (February 3, 1843 – June 1, 1919), was a politician from the U.S. state of Michigan. Fisher was born in Camden, Michigan, where he attended the public schools. He also attended Albion College and Hillsdale College. He engaged in lumbering and banking in West Bay City, where he was mayor, 1881-1884. He was a delegate to the Democratic National Convention of 1884