Lewis Ketcham Sillcox (April 30, 1886 – March 4, 1989) was an American mechanical engineer for railroads, business executive, 73rd president of the American Society of Mechanical Engineers, and recipient of the 1943 ASME Medal.Born in Germantown, Philadelphia as son of George Washington Sillcox (1844–1924) and Georgiana (Parker) Sillcox (1866–1968), Sillcox received his education in Belgium.