Leon Abgarovich Orbeli (Armenian: ???? ?????? ??????, Levon Abgari Orbeli; Russian: ???? ????????? ??????, Levon Abgarovich Orbeli; June 25, 1882 – December 9, 1958) was an Armenian physiologist active in the Russian SFSR.
He was a member of the Academies of Science of USSR and Armenian SSR (the latter was founded by his brother Joseph Orbeli).
Leon Orbeli became director of the Institute of Physiology in 1950.
Orbeli played an important part in the development of evolutionary physiology and wrote more than 200 works on experimental and theoretical science, 130 of them journal articles.