Johann Friedrich Bernhard Fischer (19 February 1852 Coburg - 2 August 1915 Dadizele) was a German bacteriologist noted for his classification system for bacteria.
After attending Casimirianum from 1862 to 1871, he was educated at the University of Berlin, received the degree of M.D. in 1875, and went to Egypt and India as member of the German Cholera Commission. In 1889, he was a member of the Plankton Expedition and 10 years later became professor at the University of Kiel. There he also became head of the Institute of Hygiene. He became generally known for his classification of bacteria. His Structure and Functions of Bacteria (2d ed., 1900), was the standard in its field.