Clark McAdams Clifford (1906 — 1998) was a highly influential American lawyer who served United States Presidents Harry S. Truman, John F. Kennedy, Lyndon B. Johnson and Jimmy Carter. He served as White House Counsel from 1946 to 1950 during the Truman Administration. Johnson named him Secretary of Defense in 1968 replacing Robert McNamara during the Vietnam War. After Johnson left office, Clifford resumed his legal practice and lobbying work, in which he was considered one of Washington's "superlawyers."