- Caecidae Gray 1850
- Caesionidae Bonaparte 1831
- Calanticidae Zevina 1978
- Caligidae Burmeister 1835
- Callanthiidae Ogilby 1899
- Callianassidae Dana 1852
- Callichthyidae Bonaparte 1838
- Callionymidae Bonaparte 1831
- Callistoplacidae Pilsbry 1893
- Callochitonidae Plate 1901
- Callorhinchidae Garman 1901
- Callyspongiidae de Laubenfels 1936
- Camaenidae Pilsbry 1895
- Camallanidae Railliet & Henry 1915
- Cambaridae Hobbs 1942
- Campanulaceae de Jussieu 1789
- Campanulariidae Johnston 1836
- Campanulinidae Hincks 1868
- Cancellothyrididae Thomson 1926
- Canidae G. Fischer de Waldheim 1817
- Cannabaceae Martynov 1820
- Canthocamptidae Brady 1880
- Capillariidae Railliet 1915
- Capitellidae Grube 1862
- Caprellidae Leach 1814
- Caprifoliaceae de Jussieu 1789
- Capsalidae Baird 1853
- Carabidae Latreille 1802
- Carangidae Lacepède 1801
- Carapidae Jordan & Fowler 1902
- Carcharhinidae D.S. Jordan & Evermann 1896
- Cardiidae Lamarck 1809
- Caristiidae T.N. Gill & H.M. Smith 1905
- Carybdeidae Gegenbaur 1857
- Caryophyllaceae de Jussieu
- Caryophylliidae Dana 1846
- Castoridae Hemprich 1820
- Catopidae Thomson 1862
- Caulerpaceae Kützing 1843
- Cavoliniidae Gray 1850 (1815)
- Centrarchidae Bleeker 1859
- Centriscidae Rafinesque 1810
- Centrolophidae Bonaparte 1846
- Centrorhynchidae Van Cleave 1916
- Cephalobidae Chitwood & Chitwood 1934
- Cephalothricidae
- Cephidae Newman 1834
- Cepolidae Rafinesque 1810
- Cerambycidae Latreille 1802
- Ceramiaceae Dumortier 1822
- Cercopithecidae Gray 1821
- Cerithiidae Fleming 1822
- Cervidae Goldfuss 1820
- Cettiidae Alström, Ericson, Olsson & Sundberg 2006
- Chaenopsidae T.N. Gill 1865
- Chaetocerotaceae Ralfs 1861
- Chaetodontidae Rafinesque 1810
- Chaetopteridae Audouin & Milne Edwards 1833
- Chalcididae Latreille 1817
- Chalinidae Gray 1867
- Champsodontidae Jordan & Snyder 1902
- Channidae Fowler 1934
- Characeae S.F. Gray 1821
- Charadriidae Vigors 1825
- Cheilodactylidae Bonaparte 1850
- Chelidridae Gray 1831
- Cheloniidae Gray 1825
- Chilodonellidae Deroux 1970
- Chironomidae Newman 1834
- Chitonidae Rafinesque 1815
- Chlidonophoridae Muir-Wood 1959
- Chlopsidae Rafinesque 1815
- Chondracanthidae Milne Edwards 1840
- Chordariaceae Greville 1830
- Chordodidae May 1919
- Chrysidoidae
- Chrysomelidae Latreille 1802
- Chrysopetalidae Ehlers 1864
- Chthamalidae Darwin 1854
- Cicadidae
- Cichlidae Heckel 1840
- Cicindelidae Latreille 1802
- Cidaridae Gray 1825
- Cimbicidae Leach 1817
- Cirolanidae Dana 1852
- Cirratulidae Ryckholdt 1851
- Citharidae de Buen 1935
- Cladorhizidae Dendy 1922
- Clausidiidae Embleton 1901
- Clausiliidae J.E. Gray 1855
- Cleptidae Morice 1900
- Cletodidae Borutsky 1926
- Clinidae Swainson 1839
- Clinostomidae Lühe 1901
- Clupeidae G. Cuvier 1817
- Clypeasteridae L. Agassiz 1835
- Cnismatocentridae Cooper 1973
- Cobitidae Swainson 1838
- Coccinellidae Latreille 1807
- Coeloplanidae Willey 1896
- Coenagrionidae Kirby 1890
- Coenobitidae Dana 1851
- Colobometridae A.H. Clark 1909
- Colubridae Oppel 1811
- Columbellidae Swainson 1840
- Columbidae Leach 1820
- Comasteridae A.H. Clark 1908
- Comatulidae Fleming 1828
- Combretaceae Robert Brown
- Commelinaceae de Mirbel 1804
- Congridae Kaup 1856
- Conidae Fleming 1822
- Conochilidae Remane 1933
- Convolutidae Graff 1905
- Convolvulaceae de Jussieu
- Cooperiidae Skrjabin & Schulz 1937
- Corallinaceae Lamouroux 1812
- Corbiculidae Gray 1847
- Cordulegasteridae Calvert 1893
- Corduliidae Sélys 1871
- Coreidae Leach 1815
- Corixidae Leach 1815
- Cornaceae von Berchtold & J. Presl 1825
- Corophiidae Leach 1814
- Corvidae Vigors 1825
- Corydalidae Leach 1815
- Corymorphidae Allman 1872
- Corynidae Johnston 1836
- Coryphaenidae Rafinesque 1810
- Cosmocercidae Railliet 1916
- Cottidae Bonaparte 1832
- Crabronidae Latreille 1802
- Crangonidae Haworth 1825
- Craniidae Menke 1828
- Cricetidae J. Fischer 1817
- Cryptobranchidae Fitzinger 1826
- Cryptogonimidae Ward 1917
- Cryptoplacidae H. Adams & A. Adams 1858
- Cryptoporidae Muir-Wood 1955
- Ctenodiscidae Sladen 1889
- Ctenoplanidae Willey 1896
- Curculionidae Latreille 1802
- Cucurbitaceae de Jussieu 1789
- Culicidae Meigen 1818
- Cupressaceae Richard ex Bartlett 1830
- Curculionidae Latreille 1802
- Cyathostomidae Yamaguti 1901
- Cyclopettidae Martínez Arbizu 2000
- Cyclophoridae Gray 1847
- Cyclopidae Rafinesque 1815
- Cyclopinidae G.O. Sars 1913
- Cyclopteridae Bonaparte 1831
- Cylichnidae H. Adams & A. Adams 1854
- Cymothoidae Leach 1818
- Cynipidae
- Cynoglossidae Jordan 1888
- Cyperaceae de Jussieu 1789
- Cypridinidae Baird 1850
- Cyprinidae Rafinesque 1815
- Cyrenidae Gray 1847
- Cystidicolidae Skrjabin 1946