Sir Oliver Simon D'Arcy Hart is a British-American economist and the Lewis P. and Linda L. Geyser University Professor at Harvard University. He received the Nobel Memorial Prize in Economic Sciences in 2016, sharing it with Bengt R. Holmström for their work on contract theory.

Hart earned his B.A. in mathematics from King's College, Cambridge, in 1969, an M.A. in economics from the University of Warwick in 1972, and a Ph.D. in economics from Princeton University in 1974.