Adolf Mauritz Fonahn (born June 15, 1873 in Hedrum, died 21 August 1940 in Oslo) was a Norwegian physician, medical historian and orientalist. He is best known for his work including those revolving around Tibetan Buddhism, Leonardo da Vinci's anatomical drawings (where he was one of the first who interpreted Leonardo's mirror writing), early Persian and Arabic medical literature, and more generally the study of medical history and Asian languages.
Fonahn is known for his diverse areas of interest and multitude of his works; these included Zur Quellenkunde der persischen Medizin (Persian Medicine and its Source) published in 1910 in Leipzig, Germany, Orm og ormmidler i nordiske medicinske skrifter fra middelalderen (? Norwegian Medicine from the Middle Ages) published in 1905, Arabic and Latin anatomical terminology: chiefly from the Middle Ages in 1922, A Palmyrene man's Name in Arabic transcription on a surgical bronze instrument in 1920, Japanese ornamented arrow-heads in 1929, and translations of multiple works for Leonardo da Vinci given out in such publications as 24 fogli della Royal Library di Windsor: Cuore: Anatomia e fisiologia (24 sheets of the Windsor Royal Library on heart anatomy and physiology)  in 1912.
- Adolf Fonahn in Norsk biografisk leksikon
- Erik Berntsens (2011). "Adolf Mauritz Fonahn". vestraat.net.
- Sami K.; Hamarneh, P.H.D. (November 1974). "Book Review" (PDF). Bulletin of New York Academy of Medicine.
- Adolf Fonhan (1968). Zur Quellenkunde der persischen Medizin.
- Adolf Fonhan (1905). Orm og ormmidler i nordiske medicinske skrifter fra middelalderen. Dybwad i komm.
- Adolf Fonhan (1922). Arabic and Latin anatomical terminology: chiefly from the middle ages. J. Dybwad (A. W. Brøggers boktrykkeri).
- Adolf Fonhan (1920). A Palmyrene man's Name in Arabic transcription on a surgical bronze instrument. Dybwad in comm.
- Adolf Fonhan (1929). Japanese ornamented arrow-heads.
- Leonardo da Vinci, trans. (Adolf Fonahn, Halfdan Hopstock, Conrad Langaard Vangensten) (1912). 24 fogli della Royal Library di Windsor: Cuore: Anatomia e fisiologia. Dybwad.