Carl Sigismund Kunth (June 18, 1788 – March 22, 1850), also Karl Sigismund Kunth or anglicized as Charles Sigismund Kunth, was a German botanist. He is known for being one of the first to study and categorise plants from the American continents, publishing Nova genera et species plantarum quas in peregrinatione ad plagam aequinoctialem orbis novi collegerunt Bonpland et Humboldt (7 vols., Paris, 1815-1825).
Born in Leipzig, Kunth became a merchant's clerk in Berlin in 1806. After meeting Alexander von Humboldt, however, who helped him attend lectures at the University of Berlin, Kunth became interested in botany. Kunth worked as Humboldt's assistant in Paris from 1813 to 1819, in which he classified the plants that had been collected by Humboldt and Aimé Bonpland during their journey through the Americas.
When Kunth returned to Berlin in 1820, he became professor of botany at the University of Berlin, as well as vice president of the botanical garden. In 1829, was elected member of the Academy of sciences of Berlin.
In 1829, he sailed for South America and during a space of three years, visited Chile, Peru, Brazil, Venezuela, Central America, and the West Indies.
After his death in 1850, the Prussian government acquired his botanical collection, which later formed part of the royal herbarium in Berlin.