Moritz Werner Fenchel (; 3 May 1905 – 24 January 1988) was a
mathematician known for his contributions to
geometry and to
optimization theory. Fenchel established the basic results of
convex analysis and nonlinear optimization theory which would, in time, serve as the foundation for
Nonlinear programming. A German-born Jew and early refugee from Nazi suppression of intellectuals, Fenchel lived most of his life in Denmark. Fenchel's monographs and lecture notes are considered influential.