Carl Ignaz Leopold Kny (6 July 1841 – 26 June 1916) was a German botanist born in Breslau.
He studied at Breslau, Munich and Berlin, where he was a pupil of Alexander Braun (1805–1877). In 1873 he became an associate professor at the University of Berlin, as well as director of the newly formed institute of plant physiology. Among his students at Berlin was plant physiologist Hermann Vöchting (1847-1917).
Leopold Kny was a specialist in research involving the morphology of fungi and cryptogams (mosses, ferns and algae). He is remembered for producing Botanische Wandtafeln, which was a series of 117 botanical wall charts that were published between 1874 and 1911. Kny's charts were known for their high level of detail, and were widely used in classrooms long after his death. They were accompanied with a 554-page textbook for explanatory purposes. Today these wall charts are housed in several different museums.
In 1891 botanist Otto Kuntze name the genus Knyaria in his honor.
His daughter Hedwig Kny married Erich Klausener on 1 August 1914 in Düsseldorf.