Clarence Francis Hiskey (1912–1998), born Clarence Szczechowski, was a Soviet espionage agent in the United States. He became active in the Communist Party USA (CPUSA) when he attended graduate school at the University of Wisconsin. He became a professor of chemistry at the University of Tennessee, Columbia University and Brooklyn Polytechnic Institute. For a time, Hiskey worked at the Tennessee Valley Authority and the University of Chicago Metallurgical Laboratory, part of the Manhattan Project. He was the father of Nicholas Sand.