Donald Lawson Turcotte (born 22 April 1932) is an American geophysicist most noted for his work on the boundary layer theory of mantle convection as part of the theory of plate tectonics. He works at the University of California, Davis. He has won awards including the Arthur L. Day Medal of the Geological Society of America, the William Bowie Medal and the Charles A. Whitten Medal of the American Geophysical Union. He is a member of the National Academy of Sciences.