Arnold Adolph Berthold or Arnold Adolf Berthold (1803 - 1861) was a Germanphysiologist and zoologist. He studied medicine in Göttingen in 1819 and wrote his thesis under the direction of Johann Friedrich Blumenbach (1752-1840). Berthold became a private lecturer in 1825 and began to teach physiology at the University of Göttingen where he spent the rest of his career. He is known as a pioneer in endocrinology due to his experiments on the role of the gonads in the development of secondary sexual characteristics. He published important works on reptiles and amphibians as well as on avianphysiology. In the field of entomology, he authored Natürliche Familien des Thierreichs (1827).
Berthold is particularly famous for his work on endocrinology. In 1849, Berthold performed ground breaking experiments with chicken castration.