Michael Chertoff is an American attorney who was the second United States Secretary of Homeland Security to serve under President George W. Bush. Chertoff also served for one additional day under President Barack Obama. He was the co-author of the USA PATRIOT Act. Chertoff previously served as a United States circuit judge of the United States Court of Appeals for the Third Circuit, as a federal prosecutor, and as Assistant U.S. Attorney General. He succeeded Tom Ridge as U.S. Secretary of Homeland Security on February 15, 2005.

The United States secretary of homeland security is the head of the United States Department of Homeland Security, the federal department tasked with ensuring public safety in the United States. The secretary is a member of the Cabinet of the United States. The position was created by the Homeland Security Act following the attacks of September 11, 2001.