Marshall Clagett (January 23, 1916, Washington, D.C. – October 21, 2005, Princeton, New Jersey) was an American historian of science who specialized in medieval science. John Murdoch describes him as "a distinguished medievalist" who was "the last member of a triumvirate [with Henry Guerlac and I. Bernard Cohen, who] … established the history of science as a recognized discipline within American universities"[1][2] while Edward Grant ranks him "among the greatest historians and scholars of the twentieth century."[3][4]