Clark McAdams Clifford was an American lawyer who served as an important political adviser to Democratic presidents Harry S. Truman, John F. Kennedy, Lyndon B. Johnson, and Jimmy Carter. His official government positions were White House Counsel (1946–1950), Chairman of the President's Intelligence Advisory Board (1963–1968), and Secretary of Defense (1968–1969); Clifford was also influential in his role as an unofficial, informal presidential adviser in various issues. A successful Washington, D.C., lawyer, he was known for his elite clientele, charming manners, and impeccable suits.