William Monroe Trotter (sometimes just Monroe Trotter, April 7, 1872 – April 7, 1934) was a newspaper editor and real estate businessman based in Boston, Massachusetts, and an activist for African-American civil rights. He was an early opponent of the accommodationist race policies of Booker T. Washington, and in 1901 founded the Boston Guardian, an independent African-American newspaper he used to express that opposition. Active in protest movements for civil rights throughout the 1900s and 1910s, he also revealed some of the differences within the African-American community. He contributed to the formation of the National Association for the Advancement of Colored People (NAACP).