Gotfryd, Bernard, photographer · Public domain

Rebuilt economics around mathematics with Foundations of Economic Analysis, then wrote Economics: An Introductory Analysis, the field's best-selling textbook, which taught generations of American students Keynesian ideas he called, with self-deprecating precision, "cafeteria Keynesianism" — taking what he found useful and leaving the rest. In 1970 he became the first American to win the Nobel Memorial Prize in Economic Sciences, and for years traded op-eds with his ideological opposite, Milton Friedman, in the pages of Newsweek.