William L. Haskin (May 31, 1841 – September 24, 1931) was a career officer in the United States Army. A Union Army veteran of the American Civil War, Haskin took part in the quashing of the 1866 and 1870 Fenian raids, when Irish nationalists attempted to organize in the United States, then invade the British dominion of Canada. In addition, he took part in the federal government's response to the Great Railroad Strike of 1877.