August David Krohn (1803–1891) was a Saint Petersburg born zoologist of German origin. He was the son of Abraham Krohn, the founder of Russia's first brewery, who had left the island of Rügen to serve in the court of Catherine the Great. He was the uncle of the fennomanfolkloristJulius Krohn. According to legend, Krohn is said to have left for Central Europe after losing to his younger brother Leopold the competition for the hand of a Vyborg mansion owner's 15-year-old daughter. He remained unmarried until his death at the age of 88.