Max Kleiber (4 January 1893 – 5 January 1976) was a Swiss agricultural biologist, born and educated in Zurich, Switzerland. Kleiber graduated from the Federal Institute of Technology as an Agricultural Chemist in 1920, earned the ScD degree in 1924, and became a private dozent after publishing his thesis The Energy Concept in the Science of Nutrition. He is credited with the description of the ratio of metabolism to body mass, which became Kleiber's law.