German biochemist who, with Leopold Ruzicka (Ružička, Leopold), was awarded the 1939 Nobel Prize for Chemistry for his work on sex hormones (sex hormone). Although forced by the Nazi government to refuse the prize, he was able to accept the honour in 1949.

Butenandt studied at the universities of Marburg and Göttingen, receiving his Ph.D. from the latter in 1927. He then taught at Göttingen and at the Institute of Technology in Danzig (now Gdańsk, Pol.). Butenandt was director of the Kaiser Wilhelm Institute (later the Max Planck Institute) for Biochemistry in Berlin beginning in 1936, and when the institute moved to Tübingen in 1945 he became a professor at the University of Tübingen. In 1956, when the institute relocated to Munich, Butenandt became a professor at the University of Munich. He also served as president of the Max Planck Society for the Advancement of Science from 1960 to 1972.

In 1929, almost simultaneously with Edward A. Doisy (Doisy, Edward Adelbert) in the United States, Butenandt isolated estrone, one of the hormones responsible for sexual development and function in females. In 1931 he isolated and identified androsterone, a male sex hormone, and in 1934, the hormone progesterone, which plays an important part in the female reproductive cycle. It was now clear that sex hormones are closely related to steroids (steroid), and after Ruzicka showed that cholesterol could be transformed into androsterone, he and Butenandt were able to synthesize both progesterone and the male hormone testosterone. Butenandt's investigations made possible the eventual synthesis of cortisone and other steroids and led to the development of birth control pills.

In the 1940s Butenandt's researches on eye-colour defects in insects proved that specific genes control the synthesis of enzymes needed in various metabolic processes, and that mutations in those genes can result in metabolic defects. In 1959, after two decades of research, Butenandt and his colleagues isolated the sex attractant of the silkworm moth, Bombyx mori, which proved to be the first known example of the important class of chemical substances known as pheromones (pheromone). He was also the first to crystallize an insect hormone, ecdysone.