John D. Marks (born 1943)[1] is the founder and former president of Search for Common Ground (SFCG), a nonprofit organization based in Washington, D.C., that focuses on international conflict management programming.

It contributed to investigative reports by Seymour Hersh in The New York Times and the decision by Frank Church to establish the United States Senate Select Committee to Study Governmental Operations with Respect to Intelligence Activities, in 1975.

Documents obtained from the CIA by Marks under Freedom of Information in 1976 showed that, in 1953, the agency considered purchasing ten kilograms of LSD, enough for 100 million doses.

[4] Marks delivered a speech on the book at Turning Point 1977, the 1977 Libertarian Party National Convention held July 12–17, at the Sheraton-Palace Hotel, in San Francisco.

[5] Marks' 1979 book, The Search for the Manchurian Candidate, describes a wide range of CIA activities during the Cold War, including unethical drug experiments as part of a mind-control and chemical interrogation research program known as Project MKUltra.