Lloyd Stowell Shapley (; June 2, 1923 – March 12, 2016) was an American mathematician and Nobel Prize-winning economist. He contributed to the fields of mathematical economics and especially game theory. Shapley is generally considered one of the most important contributors to the development of game theory since the work of von Neumann and Morgenstern. With Alvin E. Roth, Shapley won the 2012 Nobel Memorial Prize in Economic Sciences "for the theory of stable allocations and the practice of market design." Life and career Lloyd Shapley was born on June 2, 1923, in Cambridge, Massachusetts, one of the sons of astronomers Harlow Shapley and Martha Betz Shapley, both from Missouri. He attended Phillips Exeter Academy and was a student at Harvard when he was drafted in 1943. He served in the United States Army Air Corps in Chengdu, China and received the Bronze Star decoration for breaking the Soviet weather code. After the war, Shapley returned to Harvard and graduated with an A.B. in mathematics in 1948. After working for one year at the RAND Corporation, he went to Princeton University where he received a Ph.D. in 1953 based on the thesis "Additive and non-additive set functions". His thesis and post-doctoral work introduced the Shapley value and the core solution in game theory. Shapley defined game theory as "a mathematical study of conflict and cooperation." After graduating, he remained at Princeton for a short time before going back to the RAND corporation from 1954 to 1981. In 1950, while a graduate student, Shapley invented the board game So Long Sucker, along with Mel Hausner, John Forbes Nash, and Martin Shubik. Israeli economist Robert Aumann said Shapley was "the greatest game theorist of all time." From 1981 until his death, Shapley was a professor at the University of California, Los Angeles (UCLA), serving at the time of his death as a professor emeritus there, affiliated with the Mathematics and Economics departments. He died on March 12, 2016, in Tucson, Arizona, after suffering from a broken hip, at the age of 92. Shapley was an expert Kriegspiel player, and an avid baseball fan. Contribution Along with the Shapley value, stochastic games, the Bondareva–Shapley theorem (which implies that convex games have non-empty cores), the Shapley–Shubik power index (for weighted or block voting power), the Gale–Shapley algorithm for the stable marriage problem, the concept of a potential game (with Dov Monderer), the Aumann–Shapley pricing,