William Patrick Clark Jr. 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.

The deputy secretary of state of the United States is the principal deputy to the secretary of state. As of February 2024, the position is held by Kurt M. Campbell, who is serving under United States Secretary of State Antony Blinken. If the secretary of state resigns or dies, the deputy secretary of state becomes acting secretary of state until the president nominates and the Senate confirms a replacement. The position was created in 1972. Prior to July 13, 1972, the under secretary of state had been the second ranking officer of the Department of State.