John Harsanyi, Hungarian-American economist and academic, Nobel Prize laureate (d. 2000)
John Charles Harsanyi (Hungarian: Harsányi János Károly; May 29, 1920 – August 9, 2000) was a Hungarian Nobel Prize laureate economist. He moved to the United States in 1956, and spent most of his life there.

He is best known for his contributions to the study of game theory and its application to economics, specifically for his developing the highly innovative analysis of games of incomplete information, so-called Bayesian games. He also made important contributions to the use of game theory and economic reasoning in political and moral philosophy (specifically utilitarian ethics) as well as contributing to the study of equilibrium selection. For his work, he was a co-recipient along with John Nash and Reinhard Selten of the 1994 Nobel Memorial Prize in Economic Sciences. According to György Marx, he was one of The Martians.