Johannes Govertus de Man (May 2, 1850 in Middelburg – January 9, 1930 in Middelburg), was a Dutch biologist. He was assistant curator at the Rijksmuseum van Natuurlijke Historie (Dutch for national natural history museum) in Leiden, where he specialised in free-living nematodes and decapod crustaceans, although he also wrote papers on flatworms, sipunculids and, in his dissertation only, vertebrates.