Sumner McKnight Crosby, Sr. (July 29, 1909 – November 16, 1982) was an American art historian, archaeologist, and educator.
A scholar of medieval architecture, specially the Basilica of Saint-Denis, Crosby was Professor of Art History at Yale University.
His paternal grandfather was John Crosby, one of the founders of General Mills, and one of his great-grandfathers was Franklin Muzzy, a noted politician from Maine.
His professorship was interrupted by World War II as he began serving as a Special Advisor for the Roberts Commissions from 1943 to 1945, as part of the Monuments, Fine Arts, and Archives program to help recover Nazi plunder.
Crosby was awarded a Guggenheim Fellowship in 1947, and three years later, was made a Chevalier of the Legion of Honour by the Government of France.