Margaret Dye Ellis (née Dye; September 30, 1845 – July 13, 1925) was an American social reformer, lobbyist, and correspondent active in the temperance movement. She served as Superintendent, Legislation, for the National Woman's Christian Temperance Union (W.C.T.U.). in Washington, D.C. for 17 years, looking after reform measures in Congress. Throughtout those years, she contributed to the W.C.T.U.'s organ, The Union Signal, a weekly, "Our Washington Letter". She favored woman suffrage and was a social purity activist. Ellis, aided by local and State unions, helped greatly in securing the passage of many reform laws.