Dirk Arthur Kempthorne is an American politician who served as the 49th United States Secretary of the Interior from 2006 to 2009 under President George W. Bush. A member of the Republican Party, he previously served as a United States Senator from Idaho from 1993 to 1999 and the 30th governor of Idaho from 1999 to 2006.

The United States secretary of the interior is the head of the United States Department of the Interior. The secretary and the Department of the Interior are responsible for the management and conservation of most federal land along with natural resources, leading such agencies as the Bureau of Land Management, the United States Geological Survey, Bureau of Indian Affairs and the National Park Service. The secretary also serves on and appoints the private citizens on the National Park Foundation Board. The secretary is a member of the United States Cabinet and reports to the president of the United States. The function of the U.S. Department of the Interior is different from that of the interior minister designated in many other countries.