Leonard P. Liggio (July 5, 1933 – October 14, 2014) was a classical liberal author, research professor of law at George Mason University, and executive vice president of the Atlas Network in Fairfax, Virginia, USA.
In 1965 Liggio gave lectures with Russell Stetler on 'Imperialism and Anti-Imperialism: The Ideological Question in Vietnam' for the newly founded Free University of New York. Liggio provided editorial direction for Literature of Liberty: A Review of Contemporary Liberal Thought, a periodical published by the Cato Institute from 1978–1979 then by the Institute for Humane Studies from 1980–1982.
Liggio was a visiting professor of law at the Francisco Marroquin University in Guatemala City, at the Academia Istropolitana in Bratislava (Slovakia), at the Institute for Political and Economic Studies (Georgetown University) and at the University of Aix-en-Provence, France. He was executive director of the John Templeton Foundation Freedom Project at the Atlas Network, where he led the International Freedom Project from 1998 to 2003. Liggio is a distinguished senior scholar with the Institute for Humane Studies, where he served as director of Programs in History and Social Theory from 1974 to 1977, as executive vice-president from 1979 to 1980, then president from 1980 to 1989. Liggio served the Humane Studies Foundation as chairman from 1980 to 1994, then vice-chairman from 1994 to 1998.
Leonard Liggio had an international influence. In 1958, he attended his first meeting of the Mont Pelerin Society in the USA, held at Princeton University. He became a Member of the Program Committee for the Society's 1994 meeting at Cannes, France, in 1992. In 1996, he became its treasurer (until 2000) as well as a member of its Program and Planning Committee for the 1998 Society meeting in Washington, DC., and of its Board of Directors (until 2006). He became the Chairman of its Program Committee for the 2002 meeting in London, England. He was then Vice-President of the Mont Pelerin Society from 2000 to 2002, and its President from 2002 to 2004. He has been Senior Vice-President from 2004, due to leave in 2006.