Hastings Lionel Ismay, 1st Baron Ismay was a British politician, diplomat and general in the British Indian Army who was the first Secretary General of NATO. He also was Winston Churchill's chief military assistant during the Second World War.

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.