Forstmann is a German surname. Notable people with the surname include:
Arnold Forstmann (1842-1914), German artist
Gustav Forstmann (1908-1985), German naval commander
Judith Forstmann (died 2009), Argentinian politician
Julius Anthony (Tony) Forstmann, businessman
Nicholas C. Forstmann aka "Nick" (1947-2001), businessman
Theodore J. Forstmann aka "Ted" (1940-2011), businessman
Walther Forstmann (1883-1973), German U-boat commander