• Galvina Alder & Hancock, 1855 accepted as Eubranchus Forbes, 1838
• Gavina Bonaparte, 1854 accepted as Larus Linnaeus, 1758
• Gavina Bonaparte, 1854, nom. nud. accepted as Larus Linnaeus, 1758
• Gemina V.J. Chapman, 1952
• Gevuina Molina, 1782
• Gmelina Grimm in G.O. Sars, 1894 [Family: Gammaridae]
• Gmelina Linnaeus, 1753 [Family: Lamiaceae]
• Gouetina Cossmann, 1915 †
• Guavina Bleeker, 1874
• Guepinia Bastard, 1812 (uncertain) [Family: Brassicaceae]
• Guepinia E.M. Fries, 1825 [Family: Auriculariales incertae sedis]
• Guepinia Hepp, 1864 accepted as Heppia Nägeli in Hepp, 1853 [Family: Lichinaceae]
• Guerina Della Valle, 1893 accepted as Trischizostoma Boeck, 1861
• Guerinea Picquenard, 1912 accepted as Pneophyllum Kützing, 1843
• Guerinia Costa, 1853 accepted as Trischizostoma Boeck, 1861 [Family: Trischizostomatidae]
• Guerinia J. Smith, 1875 accepted as Lindsaea Dryander ex Smith, 1793 [Family: Lindsaeaceae]
• Guerinia Macquart, 1835 (unaccepted) [Family: Diptera (awaiting allocation)]
• Guerinia Robineau-Desvoidy, 1830 (uncertain > nomen dubium) [Family: Tachinidae]
• Guerinia Targioni-Tozzetti, 1868 accepted as Gueriniella Fernald, 1903 [Family: Margarodidae]
• Guerrina Odhner, 1954 (uncertain)
• Gumina Bowerbank, 1874 (unaccepted) [Family: Chondrillidae]
• Gumina Finlay, 1928 [Family: Pyramidellidae]
• Gummina Schmidt, 1862 accepted as Chondrosia Nardo, 1847
• Guolina Heydon, 1994 (uncertain)