John Nash (1928–2015) was an American mathematician who made fundamental contributions to game theory, real algebraic geometry, differential geometry, and partial differential equations.
Nash's work in 📝Game Theory — particularly the equilibrium concept that bears his name, the Nash equilibrium — formalized how rational actors behave in strategic interactions where no player benefits from unilaterally changing strategy, reshaping economics, political science, and evolutionary biology. Alongside fellow game theorists John Harsanyi and Reinhard Selten, he received the 1994 Nobel Memorial Prize in Economic Sciences for this work.
Beyond game theory, Nash made significant contributions to pure mathematics, including real algebraic geometry and the Nash embedding theorems in differential geometry. In 2015, months before his death, he and mathematician Louis Nirenberg were jointly awarded the Abel Prize — one of mathematics' highest honors — for their contributions to the field of partial differential equations.