Colin S. Gray (December 29, 1943 – February 27, 2020) was a British-American writer on geopolitics and professor of International Relations and Strategic Studies at the University of Reading, where he was the director of the Centre for Strategic Studies.^[1] In addition, he was a Senior Associate to the National Institute for Public Policy.

Gray was educated at the University of Manchester and the University of Oxford. He worked at the International Institute for Strategic Studies and the Hudson Institute, before founding the National Institute for Public Policy in Washington, D.C. He also served as a defence adviser both to the British and U.S. governments. Gray served from 1982 until 1987 in the Reagan Administration's General Advisory Committee on Arms Control and Disarmament.^[2] He taught at the University of Hull, the University of Lancaster, York University, the University of Toronto and the University of British Columbia.^[3] Gray published 30 books on military history and strategic studies, as well as numerous articles.

Gray was criticized by Alex Marshall of the University of Glasgow for his attempt to elevate Harry S. Truman's reputation to "a level of adulation far higher than the historical record could ever objectively sustain", as well as for Gray's silence on Truman's intellectual mediocrity and role in bringing about the Cold War.^[4]