O'Neill, Gerard Kitchen (1927–1992)
Gerard K. O'Neill was an American physicist at the Institute for Advanced Studies, Princeton, who, in 1969, began to work out a strategy for the future expansion of the human race into space. He championed the idea of orbital settlements in several papers1 and his book The High Frontier.2 The L5 Society was formed to advocate and develop his schemes, although O'Neill never served as an officer in this organization.
References
1. O'Neill, G. K. "The Colonization of Space," Physics Today, 27 (9), 32 (1974).
2. O'Neill, Gerard K. The High Frontier. New York: William Morrow
(1977).