John Robert Bolton (born November 20, 1948) is an American diplomat, attorney and the National Security Advisor-designate of the United States.

A nationalist and conservative, Bolton served as the United States Ambassador to the United Nations from August 2005 until December 2006 as a recess appointee by President George W. Bush. He resigned in December 2006, when the recess appointment would have otherwise ended, because he was unlikely to win confirmation from the Senate in which a newly elected Democratic Party majority would be taking control in January 2007. On March 22, 2018, President Donald Trump announced his appointment as National Security Advisor, to take office on April 9, 2018.

Bolton is currently a senior fellow at the American Enterprise Institute (AEI), senior advisor for Freedom Capital Investment Management, a Fox News Channel commentator, and of counsel to the Washington, D.C. law firm Kirkland & Ellis. He was a foreign policy adviser to 2012 presidential candidate Mitt Romney. Bolton is also involved with a number of politically conservative think tanks, policy institutes and special interest groups, including the Institute of East-West Dynamics, the National Rifle Association, the U.S. Commission on International Religious Freedom, Project for the New American Century, Jewish Institute for National Security of America (JINSA), Committee for Peace and Security in the Gulf, the Council for National Policy, and the Gatestone Institute, where he serves as the organization Chairman.