Karl Wilhelm Gottlieb Leopold Fuckel (3 February 1821 – 8 May 1876) was a German botanist who worked largely on fungi. He worked as an apothecary from 1836 to 1852, afterwards deriving income from a vineyard he owned in Oestrich im Rheingau. The species epithet in the binomen Botryotinia fuckeliana, a plant pathogen and the causal agent of gray mold disease, was named by mycologist Heinrich Anton de Bary in honor of him. Fuckel was the taxonomic authority of the mycological genera Aleuria, Phyllachora (Nitschke ex Fuckel), Plectania and Sclerotinia.