Oskar Morgenstern (1902-1977) was a German born, American economist. He was Professor of Economics first in the University of Vienna and after at Princeton University. His most important contribution to economics was his joint development of expected utility theory , with John von Neumann.
In 1944 Mogenstern and von Neumann published their joint work “Theory of Games and Economic Behavior”. In this book they formulated the expected utility hypothesis towards risk aversion which uses an expected utility function and describes the individual decision-making process. To this end, they developed a set of axioms under which the expected utility hypothesis holds, the so called von Neumann–Morgenstern utility theorem.