Leopold Loeske (24 October 1865, Hohensalza – 29 March 1935, Bad Harzburg) was a German watchmaker and amateur bryologist.
A skilled watchmaker, he was self-taught as a bryologist, collecting moss specimens in Germany, Switzerland and the French Alps during his career. Following World War I, he spent eight years working as a correspondent for a commercial institution due to financial struggles. He joined the British Bryological Society in 1934.
He died at Bad Harzburg while on a collection excursion in the Harz Mountains.
The moss genera Loeskeobryum (<small>M.Fleisch. ex Broth. 1925</small>) and Loeskypnum (<small>H.K.G.Paul, 1916</small>) are both named in his honor.
He was the author of 70 published works, including a highly regarded monograph on European Grimmiaceae, "Monographie der europäischen Grimmiaceen" (1930). Other books by Loeske include:
Loeske was editor of the bryological journal, Bryologische Zeitschrift.