David O. "Doc" Cooke (August 31, 1920 – June 22, 2002) was a United States Department of Defense civilian administrator who served under twelve Secretaries of Defense over a period of 45 years. Often called the "Mayor of the Pentagon", Cooke was the department's highest-ranking career civil servant as Director of Administration and Management, and as Director of Washington Headquarters Services. He was also responsible for administering the oath of office for many key department officials.