Leonard Liggio (born July 5, 1933) is a libertarian author, professor of law at George Mason University, and executive vice president of the Atlas Economic Research Foundation.

As part of the circle of anti-state libertarians led by Murray Rothbard during the 1950s, he played an important role in the development of modern libertarian philosophy in America.

In 1958, Liggio attended the first meeting of the Mont Pelerin Society in America, held at Princeton University. He would later serve as the Society's president from 2002 to the present.

In 1965, Rothbard, Liggio and George Resch created Left and Right: A Journal of Libertarian Thought, a publication which emphasized "common philosophical bonds uniting the anarchism and isolationism of the Old Right, and the instinctive pacifistic anarchism characterizing the New Left in the middle sixties."

Liggio is currently a Distinguished Senior Scholar with the Institute for Humane Studies amd a director of the Competitive Enterprise Institute, and serves on the boards of a large number of other libertarian think-tanks.