Carl Georg Lange (4 December 1834 – 29 May 1900) was a Danish physician who made contributions to the fields of neurology, psychiatry, and psychology.

Born to a wealthy family in Vordingborg, Denmark, Lange attended medical school at the University of Copenhagen and graduated in 1859 with a reputation for brilliance.

Based on observations he made of his patients' urine, he hypothesized that the illness was related to an excess of uric acid in the blood and advocated for methods of reducing this substance, including the use of lithium.

His recommendations were discarded by the psychiatric community, as was his nosological assertions of the uniqueness of the disease.

Lithium was later found in 1949 to be an effective treatment for mood disorders, although the concept of a uric acid diathesis was fully discredited.