Jordan Carson Mark (July 6, 1913 – March 2, 1997) was a Canadian-born mathematician best known for his work on developing nuclear weapons for the United States at the Los Alamos National Laboratory. Mark joined the Manhattan Project in 1945, and continued to work at Los Alamos under the leadership of Norris Bradbury after World War II ended. He became the leader of the Theoretical Division at the laboratory in 1947, a position he held until 1973.