• Glavia Navás, 1916 (uncertain)
• Gluvia Koch, 1842
• Gocevia Valkanov, 1934
• Gravia Polenova, 1952 †
• Greefia Singh & Hanumaiah, 1979 (uncertain)
• Greenia Hoeppli & Chu, 1932 accepted as Rogerus Hoeppli & Chu, 1934 [Family: Rhabdolaimidae]
• Greenia Kirby, 1896 (uncertain) [Family: Diapheromeridae]
• Greenia Nuttall, 1835 accepted as Limnodea L.H. Dewey in J.M. Coulter, 1894 [Family: Poaceae]
• Greenia Oudemans, 1901 accepted as Dinogamasus Kramer, 1898 [Family: Laelapidae]
• Greenia S. Wallman, 1791 (uncertain) [Family: Liliaceae]
• Greffia Reibisch, 1905 accepted as Alciopa Audouin & Milne-Edwards, 1833
• Greggia A. Gray, 1852 accepted as Nerisyrenia E.L. Greene, 1900 [Family: Brassicaceae]
• Greggia Engelmann in Wislizenus, 1848 (unaccepted) [Family: Rosaceae]
• Greggia Solander ex J. Gaertner, 1788 accepted as Eugenia Linnaeus, 1753 [Family: Myrtaceae]
• Gregoia Fehse, 2015
• Greigia E. Regel, 1865
• Greira Erlanger, 1993 † (uncertain)
• Grella de Laubenfels, 1936 accepted as Crella Gray, 1867
• Grellia Levine, 1973
• Gremlia J.A. Nieuwland, 1916 accepted as Chondromyces Berkeley & M.A. Curtis, 1874 (Approved Lists, 1980)
• Grensia Ross, 1944
• Gretna Evans, 1937
• Grevea Baillon, 1884
• Grevya Hilzheimer, 1912 accepted as Equus Linnaeus, 1758
• Grewia Linnaeus, 1753
• Greyia W.J. Hooker & W.H. Harvey, 1859
• Gruevia Warchalowski, 1974
• Trevia Linnaeus, 1753 (unaccepted > nomen nudum)