Ga
- Garhundacystis I.Kostikov & L.Hoffmann, 2000
- Garwoodia Alan Wood, 1941
- Gayralia K.L.Vinogradova, 1969
- Gayraliaceae K.L. Vinogradova, 1969
Ge
- Gemellicystis Teiling, 1946
- Gemina V.J.Chapman, 1952
- Geminella Turpin, 1828
- Geminellopsis A.A.Korschikov, 1939
- Gemmichara Zhen Wang, 1984
- Gemmiphora A.Skabichevskii, 1931
- Geppella
- Geppina
Gi
Gigantochloris Pascher, 1927
- Gigantochloris permaxima Pascher 1927 [1]
Chlorophyta → Chlorophyceae → Volvocales → Chlamydomonadaceae
- Gilbertsmithia M.O.P.Iyengar, 1975
- Girvanella
Gl
- Glenobotrydion J.W.Schopf, 1968
- Glenogonium Diesing
- Glenomorum Ehrenberg
- Globator L.Grambast
- Globophycus
- Globulina Link
- Globulinea T.Ulke
- Glochiococcus G.B.De Toni, 1888
- Gloeoactinium G.M.Smith, 1926
- Gloeococcus A.Braun, 1850
- Gloeocystaceae
- Gloeocystis Nägeli, 1849
- Gloeocystopsis G.M.Smith, 1916
- Gloeodendraceae
- Gloeodendron Korshikov, 1916
- Gloeomonas Klebs, 1886
- Gloeoplax Schmidle, 1899
- Gloeotaenium Hansgirg, 1890
- Gloeotila Kützing, 1843
- Gloeotilaceae
- Gloeotilopsis Iyengar & Philipose, 1956
- Gloiodictyon C.Agardh, 1830
- Gloxidium Korshikov, 1931
Gan
- Gnathum
Go
- Golenkinia Chodat, 1894
- Golenkiniaceae (Korshikov) Komárek, 1979
- Golenkiniopsis Korshikov, 1953
- Gomontia Bornet & Flahault, 1888
- Gomontiaceae De Toni, 1889
- Gonatoblaste
- Gonatoblaste J.Huber, 1892
- Gonatonema Wittrock, 1878
- Gongrosira Kützing, 1843
- Gongrosirella P.[J.L.] Dangeard, 1970
- Goniaceae (Pascher) Pascher, 1931
- Gonium O.F.Müller, 1773
Gr
- Graesiella T.Kalina & M.Puncochárová, 1987
- Granulochloris Pascher & Jahoda, 1928
- Granulocystis Hindák, 1977
- Granulocystopsis Hindák, 1977
- Granuochloris Pascher & Jahoda, 1928
Gu
- Gungnir T.Nakada, 2008
Gy
- Györffyana Kol & F.Chodat, 1934
Gyromitus Skuja, 1939
- Gyromitus cordiformis Skuja
- Gyromitus distomatus Skuja, 1939
Chlorophyta → Prasinophyceae → Pyramimonadales → Polyblepharidaceae