Charles Howard McIlwain (March 15, 1871 – June 1, 1968) was an American historian and political scientist. He won the Pulitzer Prize for History in 1924. He was educated at Princeton University and Harvard University and taught at both institutions, as well as the University of Oxford, Miami University, and Bowdoin College. Though he trained as a lawyer, his career was mostly academic, devoted to constitutional history. He was a member of several learned societies and served as President of the American Historical Association in 1935–36.