1. Gadidae Rafinesque 1810
2. Galatheidae Samouelle 1819
3. Gammaridae Leach 1814
4. Ganeriidae Sladen 1889
5. Garryaceae Lindley 1834
6. Gasterosteidae Bonaparte 1832
7. Gaviidae Coues 1903
8. Gelidiaceae Kutzing 1843
9. Gempylidae T.N. Gill 1862
10. Geoemydidae Theobald 1868
11. Geometridae Leach 1815
12. Geotrupidae Latreille 1802
13. Gerreidae Bleeker 1859
14. Gerridae Leach 1815
15. Geryoniidae Eschscholtz 1829
16. Gigantapseudidae Kudinova-Pasternak 1978
17. Gigartinaceae Kuetzing 1843
18. Ginglymostomatidae T.N. Gill 1862
19. Glauconomidae Gray 1853
20. Gliridae Muirhead in Brewster 1819
21. Glossiphoniidae Vaillant 1890
22. Glugeidae Thelohan 1892
23. Glyceridae Grube 1850
24. Glycymerididae Dall 1908 (1847)
25. Glyphocrangonidae Smith 1884
26. Gnathostomatidae Railliet 1895
27. Gobiesocidae Bleeker 1860
28. Gobiidae G. Cuvier 1816
29. Gomphidae Rambur 1842
30. Goneplacidae MacLeay 1838
31. Gongylonematidae Hall 1916
32. Goniasteridae Forbes 1841
33. Gonorynchidae Richardson 1848
34. Goodeniaceae Robert Brown
35. Gordiidae May 1919
36. Gorgonocephalidae Ljungman 1867
37. Gracilariaceae Nägeli 1847
38. Grapsidae MacLeay 1838
39. Gryphaeidae Vialov 1936
40. Guitarridae Dendy 1924
41. Guyanemidae Petter 1974
42. Gwynioidea MacKinnon 2006
43. Gymnophallidae Odhner 1900
44. Gymnuridae Fowler 1934
45. Gynodiastylidae Stebbing 1912
46. Gyrinidae Latreille 1802
47. Gyrodactylidae