Gmelin may refer to:
- Gmelin database, a German handbook/encyclopedia of inorganic compounds initiated by Leopold Gmelin
- People
- Carl Christian Gmelin (1762-1837), a German botanist; author of "Flora Badensis, Alsatica et confinium regionum cis- et transrhenania" (1806)
- Charles Gmelin (1872–1950), a British Olympic athlete
- Christian Gottlieb Gmelin (1792–1860), a German chemist and mineralogist
- Eberhardt Gmelin, who described a purported case of dissociative identity disorder in 1791
- Herta Däubler-Gmelin (born 1943), a German politician (SPD), former German Minister of Justice
- Johann Friedrich Gmelin (1748–1804), a German naturalist; publisher of the Systema Naturae of Carolus Linnaeus
- Johann Georg Gmelin (1709–1755), a German naturalist; explorer of Siberia, author of Flora Siberica
- Leopold Gmelin (1788–1853), a German chemist
- Philipp Friedrich Gmelin (1721-1768), a German botanist and chemist
- Samuel Gottlieb Gmelin (1744–1774), a German naturalist; author of Historia Fucorum, the first work on marine biology