Joseph Slepian (February 11, 1891 – December 19, 1969)was an American electrical engineer known for his contributions to the developments of electrical apparatus and theory. Born in Boston, MA of Jewish Russian immigrants, he studied mathematics at Harvard University, from which he was awarded a B.Sc. (1911), a M.Sc. (1912) and Ph.D. on the thesis On the Functions of a Complex Variable Defined by an Ordinary Differential Equation of the First Order and First Degree advised by George Birkhoff (1913). Meanwhile, he also worked at Boston Elevated Railway.