William P. Clark Jr., American judge and politician, 12th United States National Security Advisor (b. 1931)

William Patrick Clark Jr. (October 23, 1931 – August 10, 2013) was an American rancher, judge, and public servant who served under President Ronald Reagan as the Deputy Secretary of State from 1981 to 1982, United States National Security Advisor from 1982 to 1983, and the Secretary of the Interior from 1983 to 1985.