Johan Scharffenberg (23 November 1869 – 1 February 1965) was a Norwegian psychiatrist, politician, speaker and writer.
Scharffenberg was born in Moss as the son of military officer Hedvard Carl Scharffenberg (1819–1893) and Caroline Fredrikke Dietrichson (1825–1876). He was a nephew of priest Johannes W. C. Dietrichson. The family soon moved from Moss, and Scharffenberg grew up in Kristiania, Hamar and Molde. He finished his secondary education in 1888, enrolled in medicine studies in 1889 and took the cand.med. degree in 1897.
Scharffenberg served as a physician and psychiatrist at psychiatric institutions and prisons, working in Trondhjem from 1903 to 1904 and then in Kristiania. He worked at the prison Botsfengselet from 1919 to 1940 and was a chief physician at Oslo Hospital from 1922 to late 1945, except for 1941 to early 1945. In 1976, a bust of him was raised at Oslo Hospital.
He was an active participant in the contemporary debates, starting in the late 1880s. He issued the poetry collection Hjemløse Sange ('Homeless Songs') as early as in 1889, under the pseudonym Kai Lykke. In 1899 he wrote the book Reform av den medicinske undervisning ('Reform of the Medical Training'), which became unpopular in academic circles at the time. After issuing the three-volume work Bidrag til de norske lægestillingers historie før 1800 ('Contributions to the History of Norwegian Medical Positions Before 1800) in 1904 and 1905, he applied for a fellowship at the Royal Frederick University in 1908. The Faculty of Medicine granted him the fellowship, but this was stopped by the Collegium Academicum (the university's board). Scharffenberg would later attract criticism by rejecting other methods, including that of Wilhelm Reich. He argued for less use of alcohol in the society, and was a member of the Alcohol Commission of 1910, which was established on his initiative.