The secretary general of NATO is the chief civil servant of the North Atlantic Treaty Organization (NATO), an intergovernmental military alliance with 32 member states. The officeholder is an international diplomat responsible for coordinating the workings of the alliance, leading NATO's international staff, chairing the meetings of the North Atlantic Council and most major committees of the alliance, with the notable exception of the NATO Military Committee, as well as acting as NATO's spokesperson. The secretary general does not have a military command role; political, military and strategic decisions ultimately rest with the member states. Together with the Chair of the NATO Military Committee and the supreme allied commander, the officeholder is one of the foremost officials of NATO.

The North Atlantic Treaty Organization, also called the North Atlantic Alliance, is an intergovernmental military alliance of 32 member states—30 European and 2 North American. Established in the aftermath of World War II, the organization implements the North Atlantic Treaty, signed in Washington, D.C., on 4 April 1949. NATO is a collective security system: its independent member states agree to defend each other against attacks by third parties. During the Cold War, NATO operated as a check on the threat posed by the Soviet Union. The alliance remained in place after the dissolution of the Soviet Union and the Warsaw Pact, and has been involved in military operations in the Balkans, the Middle East, South Asia and Africa. The organization's motto is animus in consulendo liber. The organization's strategic concepts include deterrence.