| Acalyptonotidae Walter, 1911 | | 3 | Species | Taxom |
| Acanthoctenidae Simon, 1892 | | 0 | Species | Taxom |
| Acanthoscorpionidae Kjellesvig-W..., 1986 | | 1 | Species | Taxom |
| Acaridae Latreille, 1802 | Acarid mites | 110 | Species | Taxom |
| Acaronychidae Grandjean, 1932 | | 6 | Species | Taxom |
| Acarophenacidae Cross, 1965 | | 10 | Species | Taxom |
| Achipteriidae Thor, 1929 | | 45 | Species | Taxom |
| Actinopodidae Simon, 1892 | Mouse Spiders | 112 | Species | Taxom |
| Adamystidae Cunliffe, 1957 | | 6 | Species | Taxom |
| Adelphacaridae Grandjean, 1954 | | 2 | Species | Taxom |
| Aeroglyphidae Zakhvatkin, 1941 | | 0 | Species | Taxom |
| Agelenidae C. L. Koch, 1837 | Agelenid Spiders | 305 | Species | Taxom |
| Agoristenidae Silhavy, 1973 | | 63 | Species | Taxom |
| Aleurodamaeidae Paschoal & J..., 1985 | | 2 | Species | Taxom |
| Algophagidae Fain, 1974 | | 11 | Species | Taxom |
| Alicorhagiidae Grandjean, 1939 | | 1 | Species | Taxom |
| Alloptidae Gaud, 1957 | | 18 | Species | Taxom |
| Alycidae Canestrini &..., 1877 | | 11 | Species | Taxom |
| Amaurobiidae Thorell, 1870 | Amaurobiids | 165 | Species | Taxom |
| Amblyommidae Banks, 1907 | | 204 | Species | Taxom |
| Ameridae Grandjean, 1965 | | 4 | Species | Taxom |
| Ameronothridae Willmann, 1931 | | 15 | Species | Taxom |
| Ameroseiidae Evans, 1961 | | 35 | Species | Taxom |
| Ametroproctidae Subías, 2004 | | 7 | Species | Taxom |
| Ammotrechidae Roewer, 1934 | Curve-faced solifugid | 119 | Species | Taxom |
| Ammoxenidae Simon, 1893 | Ammoxenid spiders | 0 | Species | Taxom |
| Amphinectidae Forster & Wi..., 1973 | Amphinectid spiders | 16 | Species | Taxom |
| Analgidae Trouessart &..., 1884 | Feather mites | 13 | Species | Taxom |
| Anamidae Simon, 1889 | | 40 | Species | Taxom |
| Anapidae Simon, 1895 | Anapid spiders | 67 | Species | Taxom |
| Anderemaeidae Balogh, 1972 | | 21 | Species | Taxom |
| Anisitsiellidae Koenike, 1910 | | 23 | Species | Taxom |
| Antennochelidae Lindquist & ..., 2014 | | 2 | Species | Taxom |
| Antennophoridae Berlese, 1892 | | 3 | Species | Taxom |
| Anthracomartidae Haase, 1890 | | 8 | Species | Taxom |
| Anthracosironidae Pocock, 1903 | | 1 | Species | Taxom |
| Anthracotarbidae (Kjellesvig-W..., 1969) | | 1 | Species | Taxom |
| Antrodiaetidae Gertsch, 1940 | Folding trapdoor spider | 36 | Species | Taxom |
| Anyphaenidae Bertkau, 1878 | Anyphaenid sac spiders | 662 | Species | Taxom |
| Anystidae Oudemans, 1936 | Whirligig Mites | 12 | Species | Taxom |
| Aphantomartidae (Petrunkevitch, 1945) | | 1 | Species | Taxom |
| Aphelacaridae Grandjean, 1954 | | 0 | Species | Taxom |
| Apheviderulicidae Gerecke, Smi..., 1999 | | 1 | Species | Taxom |
| Apionacaridae Gaud & Atyeo, 1977 | | 1 | Species | Taxom |
| Araneidae Simon, 1895 | Golden orb web spiders | 1692 | Species | Taxom |
| Arborichthoniidae J. & P. Balogh, 1992 | | 1 | Species | Taxom |
| Arceremaeidae Balogh, 1972 | | 8 | Species | Taxom |
| Archaeidae C. L. Koch &..., 1854 | Archaeid spiders | 1 | Species | Taxom |
| Architarbidae Karsch, 1882 | | 15 | Species | Taxom |
| Arctacaridae Evans, 1955 | | 2 | Species | Taxom |
| Arenohydracaridae Cook, 1974 | | 3 | Species | Taxom |
| Argasidae C. L. Koch, 1844 | Soft tick | 186 | Species | Taxom |
| Arrenuridae Thor, 1900 | | 258 | Species | Taxom |
| Arthrolycosidae Fritsch, 1904 | | 2 | Species | Taxom |
| Arthromygalidae Petrunkevitch, 1923 | | 1 | Species | Taxom |
| Ascidae Oudemans, 1905 | | 189 | Species | Taxom |
| Ascouracaridae Gaud & Atyeo, 1976 | | 7 | Species | Taxom |
| Askawachidae Kury & Carvalho, 2020 | | 1 | Species | Taxom |
| Assamiidae Sørensen, 1884 | | 2 | Species | Taxom |
| Astegistidae Balogh, 1961 | | 21 | Species | Taxom |
| Atemnidae Chamberlin, 1931 | | 23 | Species | Taxom |
| Athienemanniidae Viets, 1922 | | 8 | Species | Taxom |
| Athyreacaridae Lindquist, K..., 1990 | | 1 | Species | Taxom |
| Atopochthoniidae Grandjean, 1949 | | 3 | Species | Taxom |
| Atopomelidae Fain, 1972 | | 30 | Species | Taxom |
| Aturidae Thor, 1900 | | 177 | Species | Taxom |
| Atypidae Thorell, 1870 | Atypical tarantulas | 10 | Species | Taxom |
| Audycoptidae (Lavoipierre, 1964) | | 5 | Species | Taxom |
| Austrochilidae Zapfe, 1955 | Austrochilid spiders | 11 | Species | Taxom |
| Autognetidae Grandjean, 1960 | | 11 | Species | Taxom |
| Avenzoariidae Oudemans, 1905 | | 26 | Species | Taxom |
| Bandakiopsidae Panesar, 2004 | | 1 | Species | Taxom |
| Barbutiidae Robaux, 1975 | | 3 | Species | Taxom |
| Barychelidae Simon, 1889 | Brush-footed trapdoors | 114 | Species | Taxom |
| Basilobelbidae Balogh, 1961 | | 3 | Species | Taxom |
| Bdellidae Dugès, 1834 | Snout Mites | 28 | Species | Taxom |
| Belbidae (Willmann, 1931) | | 2 | Species | Taxom |
| Biantidae Thorell, 1889 | | 21 | Species | Taxom |
| Blattisociidae (Garman, 1948) | | 184 | Species | Taxom |
| Bochicidae Chamberlin, 1930 | | 43 | Species | Taxom |
| Bogatiidae Motas & Tana..., 1948 | | 1 | Species | Taxom |
| Bothriuridae Simon, 1880 | | 186 | Species | Taxom |
| Brachychthoniidae Thor, 1934 | | 86 | Species | Taxom |
| Branchioscorpionidae Kjellesvig-W..., 1986 | | 1 | Species | Taxom |
| Buthidae C. L. Koch, 1837 | Arrowbreasted scorpions | 642 | Species | Taxom |
| Caddidae Banks, 1892 | | 8 | Species | Taxom |
| Caeculidae Berlese, 1883 | Rake-legged mites | 41 | Species | Taxom |
| Calcitronidae Petrunkevitch, 1945 | | 1 | Species | Taxom |
| Caleremaeidae Grandjean, 1965 | | 12 | Species | Taxom |
| Caligonellidae Grandjean, 1944 | | 14 | Species | Taxom |
| Caloppiidae (Balogh, 1960) | | 5 | Species | Taxom |
| Calyptostomatidae Oudemans, 1923 | | 2 | Species | Taxom |
| Camerobiidae Southcott, 1957 | Stilt-legged mites | 56 | Species | Taxom |
| Camisiidae Oudemans, 1900 | | 11 | Species | Taxom |
| Canestriniidae Berlese, 1884 | | 139 | Species | Taxom |
| Caponiidae Simon, 1890 | Caponiid spiders | 149 | Species | Taxom |
| Caraboacaridae Mahunka, 1970 | | 2 | Species | Taxom |
| Caraboctonidae Kraepelin, 1905 | | 26 | Species | Taxom |
| Carabodidae Koch, 1837 | | 105 | Species | Taxom |
| Carpoglyphidae Oudemans, 1923 | Driedfruit mites | 4 | Species | Taxom |
| Castriidinychidae Hirschmann, 1979 | | 17 | Species | Taxom |
| Celaenopsidae Berlese, 1892 | | 12 | Species | Taxom |
| Cepheidae (Berlese, 1896) | | 7 | Species | Taxom |
| Cepheusidae Berlese, 1896 | | 36 | Species | Taxom |
| Ceratokalummidae Balogh, 1970 | | 10 | Species | Taxom |
| Ceratoppiidae (Kunst, 1971) | | 31 | Species | Taxom |
| Ceratozetidae Jacot, 1925 | | 165 | Species | Taxom |
| Cercomegistidae Trägårdh, 1937 | | 3 | Species | Taxom |
| Ceresellidae P. G. Pavlit..., 1993 | | 1 | Species | Taxom |
| Cerocepheidae Subías, 2004 | | 2 | Species | Taxom |
| Ceromidae Purcell, 1903 | | 1 | Species | Taxom |
| Chactidae Reginald Inn..., 1893 | Fatclaw scorpions | 261 | Species | Taxom |
| Chaetodactylidae Zakhvatkin, 1941 | | 45 | Species | Taxom |
| Chamobatidae Thor, 1937 | | 11 | Species | Taxom |
| Chappuisididae Motas & Tana..., 1946 | | 8 | Species | Taxom |
| Chapuisididae | | 6 | Species | Taxom |
| Charassobatidae Grandjean, 1958 | | 7 | Species | Taxom |
| Charinidae Quintero, 1986 | | 2 | Species | Taxom |
| Charontidae Simon, 1892 | | 91 | Species | Taxom |
| Cheiridiidae Hansen, 1893 | | 42 | Species | Taxom |
| Cheliferidae Risso, 1826 | | 97 | Species | Taxom |
| Chernetidae Menge, 1855 | | 425 | Species | Taxom |
| Cheylabididae Gaud, 1983 | | 1 | Species | Taxom |
| Cheyletidae Leach, 1815 | | 171 | Species | Taxom |
| Chirodiscidae Trouessart, 1892 | | 20 | Species | Taxom |
| Chirorhynchobiidae Fain, 1967 | | 0 | Species | Taxom |
| Chortoglyphidae Berlese, 1897 | | 4 | Species | Taxom |
| Chthoniidae Daday, 1888 | | 319 | Species | Taxom |
| Chyzeriidae Womersley, 1954 | | 1 | Species | Taxom |
| Circocyllibamidae Sellnick, 1926 | | 3 | Species | Taxom |
| Cithaeronidae Simon, 1893 | Cithaeronid spiders | 2 | Species | Taxom |
| Cloacaridae Camin, Moss,..., 1967 | | 8 | Species | Taxom |
| Clubionidae Wagner, 1887 | Clubiones | 176 | Species | Taxom |
| Cocceupodidae Jesionowska, 2010 | | 8 | Species | Taxom |
| Collohmanniidae Grandjean, 1958 | | 1 | Species | Taxom |
| Coprozerconidae Moraza & Lin..., 1999 | | 0 | Species | Taxom |
| Corinnidae Karsch, 1880 | Ant-like Sac Spiders | 748 | Species | Taxom |
| Cosmetidae C. L. Koch, 1839 | | 764 | Species | Taxom |
| Cosmochthoniidae Grandjean, 1946 | | 13 | Species | Taxom |
| Cranaidae Roewer, 1913 | | 24 | Species | Taxom |
| Crotalomorphidae Lindquist & ..., 2002 | | 1 | Species | Taxom |
| Crotoniidae Thorell, 1876 | | 70 | Species | Taxom |
| Cryptogeobiidae Kury, 2014 | | 33 | Species | Taxom |
| Cryptognathidae Luxton, 1973 | | 21 | Species | Taxom |
| Crypturoptidae Gaud, Atyeo ..., 1973 | | 3 | Species | Taxom |
| Ctenacaridae Grandjean, 1954 | | 6 | Species | Taxom |
| Ctenidae Keyserling, 1877 | Tropical wolf spiders | 373 | Species | Taxom |
| Ctenizidae Thorell, 1887 | Cork-lid trapdoor spider | 65 | Species | Taxom |
| Cunaxidae Thor, 1902 | Predatory Mites | 41 | Species | Taxom |
| Cuneoppiidae Balogh, 1983 | | 1 | Species | Taxom |
| Curculioididae Cockerell, 1916 | | 7 | Species | Taxom |
| Cyatholipidae Simon, 1894 | Cyatholipid spiders | 1 | Species | Taxom |
| Cybaeidae Banks, 1892 | Pond Water Spiders | 102 | Species | Taxom |
| Cycloctenidae Simon, 1898 | Scuttling spiders | 1 | Species | Taxom |
| Cymbaeremaeidae Sellnick, 1928 | | 53 | Species | Taxom |
| Cyrtaucheniidae Simon, 1892 | Cyrtaucheiid spiders | 127 | Species | Taxom |
| Cytoditidae Oudemans, 1908 | | 2 | Species | Taxom |
| Daesiidae Kraepelin, 1899 | | 18 | Species | Taxom |
| Damaeidae Berlese, 1896 | | 118 | Species | Taxom |
| Damaeolidae Grandjean, 1965 | | 5 | Species | Taxom |
| Dampfiellidae Balogh, 1961 | | 34 | Species | Taxom |
| Dasyponyssidae Fonseca, 1940 | | 2 | Species | Taxom |
| Dasythyreidae Walter & Gerson, 1998 | | 2 | Species | Taxom |
| Deinopidae C. L. Koch, 1850 | Net-casters | 22 | Species | Taxom |
| Demodecidae Nicolet, 1855 | Follicle mites | 50 | Species | Taxom |
| Dendroeremaeidae Behan-Pellet..., 2005 | | 2 | Species | Taxom |
| Deraiophoridae Trägårdh, 1952 | | 23 | Species | Taxom |
| Dermanyssidae Kolenati, 1859 | Dermanyssid mites | 25 | Species | Taxom |
| Dermationidae Fain, 1965 | | 14 | Species | Taxom |
| Dermoglyphidae Mégnin & Tro..., 1884 | | 3 | Species | Taxom |
| Desidae Pocock, 1895 | Desid spiders | 20 | Species | Taxom |
| Devonacaridae Norton, 1988 | | 1 | Species | Taxom |
| Diarthrophallidae Trägårdh, 1946 | | 30 | Species | Taxom |
| Dictynidae O. P-Cambridge, 1871 | Dictynid spiders | 467 | Species | Taxom |
| Digamasellidae Evans, 1957 | | 52 | Species | Taxom |
| Diguetidae F. O. Pickar..., 1899 | Coneweb spiders | 16 | Species | Taxom |
| Dinychidae Berlese, 1916 | | 13 | Species | Taxom |
| Diplocentridae Karsch, 1880 | Spinysting scorpions | 4 | Species | Taxom |
| Diplogyniidae Trägårdh, 1941 | | 7 | Species | Taxom |
| Dipluridae Simon, 1889 | Curtainweb Spiders | 158 | Species | Taxom |
| Diptilomiopidae Boczek, 1964 | | 14 | Species | Taxom |
| Discozerconidae Berlese, 1910 | | 2 | Species | Taxom |
| Dolichocybidae Mahunka, 1970 | | 3 | Species | Taxom |
| Dracochelidae Schawaller, ..., 1991 | | 1 | Species | Taxom |
| Drymobatidae J. & P. Balogh, 1984 | | 2 | Species | Taxom |
| Drymusidae Simon, 1893 | Drymusid spiders | 14 | Species | Taxom |
| Dysderidae C. L. Koch, 1837 | Dysderid spiders | 33 | Species | Taxom |
| Dytiscacaridae Hajikanbar a..., 2018 | | 2 | Species | Taxom |
| Echimyopodidae Fain, 1967 | | 4 | Species | Taxom |
| Elliptochthoniidae Norton, 1975 | | 1 | Species | Taxom |
| Eniochthoniidae Grandjean, 1947 | | 4 | Species | Taxom |
| Entonyssidae Ewing, 1922 | | 10 | Species | Taxom |
| Eobuthidae Kjellesvig-W..., 1986 | | 1 | Species | Taxom |
| Eophrynidae Karsch, 1882 | | 7 | Species | Taxom |
| Eoscorpiidae Scudder, 1884 | | 7 | Species | Taxom |
| Epactozetidae Grandjean, 1930 | | 9 | Species | Taxom |
| Epedanidae Sørensen, 1886 | | 6 | Species | Taxom |
| Epicriidae Berlese, 1885 | | 1 | Species | Taxom |
| Epidermoptidae Trouessart, 1892 | | 20 | Species | Taxom |
| Epilohmanniidae Oudemans, 1923 | | 21 | Species | Taxom |
| Epimyodicidae Fain, Lukosc..., 1982 | | 2 | Species | Taxom |
| Eremaeidae Oudemans, 1900 | | 58 | Species | Taxom |
| Eremaeozetidae Piffl, 1972 | | 17 | Species | Taxom |
| Eremellidae Balogh, 1961 | | 5 | Species | Taxom |
| Eremobatidae Kraepelin, 1899 | | 228 | Species | Taxom |
| Eremobelbidae Balogh, 1961 | | 13 | Species | Taxom |
| Eremulidae Grandjean, 1965 | | 16 | Species | Taxom |
| Eresidae C. L. Koch, 1851 | Eresid spiders | 5 | Species | Taxom |
| Ereynetidae Schrank, 1776 | | 25 | Species | Taxom |
| Eriophyidae Nalepa, 1898 | Blister mites | 302 | Species | Taxom |
| Erythracaridae (Oudemans, 1936) | | 2 | Species | Taxom |
| Erythraeidae Oudemans, 1902 | | 145 | Species | Taxom |
| Escadabiidae Kury & Pérez, 2003 | | 9 | Species | Taxom |
| Euctenizidae (Raven, 1985) | Wafer-lid trapdoor spiders | 1 | Species | Taxom |
| Euglycyphagidae Fain & Philips, 1977 | | 1 | Species | Taxom |
| Eukoeneniidae Condé, 1965 | | 27 | Species | Taxom |
| Eulohmanniidae Grandjean, 1931 | | 1 | Species | Taxom |
| Eupalopsellidae Willmann, 1952 | | 6 | Species | Taxom |
| Euphthiracaridae Jacot, 1930 | | 109 | Species | Taxom |
| Eupodidae Strandtmann, 1967 | Eupodid mites | 15 | Species | Taxom |
| Euscorpiidae Laurie, 1896 | Shorttail scorpions | 25 | Species | Taxom |
| Eustathiidae Oudemans, 1905 | | 17 | Species | Taxom |
| Eutegaeidae Balogh, 1965 | | 9 | Species | Taxom |
| Euzerconidae Trägårdh, 1938 | | 8 | Species | Taxom |
| Eviphididae Berlese, 1913 | | 12 | Species | Taxom |
| Eylaidae Leach, 1815 | | 38 | Species | Taxom |
| Falculiferidae Oudemans, 1905 | | 13 | Species | Taxom |
| Feaellidae Ellingsen, 1906 | | 1 | Species | Taxom |
| Fedrizziidae Trägårdh, 1937 | | 2 | Species | Taxom |
| Feltriidae Viets, 1926 | | 31 | Species | Taxom |
| Ferradasiidae Cook, 1980 | | 1 | Species | Taxom |
| Filistatidae Ausserer, 1867 | Crevice weaver | 73 | Species | Taxom |
| Fissiphalliidae (Martens, 1988) | | 6 | Species | Taxom |
| Fortuyniidae Hammen, 1963 | | 8 | Species | Taxom |
| Freyanidae Dubinin, 1953 | | 7 | Species | Taxom |
| Frontipodopsidae Viets, 1931 | | 3 | Species | Taxom |
| Gabuciniidae Gaud & Atyeo, 1975 | | 8 | Species | Taxom |
| Galeodidae Sundevall, 1833 | | 5 | Species | Taxom |
| Gallieniellidae Millot, 1947 | Gallieniellid spiders | 2 | Species | Taxom |
| Galumnellidae Piffl, 1970 | | 5 | Species | Taxom |
| Galumnidae Jacot, 1925 | | 210 | Species | Taxom |
| Garnettiidae Dubinin, 1962 | | 1 | Species | Taxom |
| Garypidae Simon, 1879 | | 21 | Species | Taxom |
| Garypinidae Daday, 1888 | | 44 | Species | Taxom |
| Gastronyssidae Fain, 1956 | | 6 | Species | Taxom |
| Gaudiellidae Atyeo, Baker..., 1974 | | 1 | Species | Taxom |
| Gaudoglyphidae (W.A. Bruce &..., 1976) | | 1 | Species | Taxom |
| Gehypochthoniidae Strenzke, 1963 | | 4 | Species | Taxom |
| Geogarypidae Chamberlin, 1930 | | 17 | Species | Taxom |
| Gigantoscorpionidae Kjellesvig-W..., 1986 | | 1 | Species | Taxom |
| Glycyphagidae De Geer, 1778 | | 63 | Species | Taxom |
| Gnaphosidae Pocock, 1898 | Flat-bellied ground spiders | 807 | Species | Taxom |
| Gonyleptidae Sundevall, 1833 | | 1079 | Species | Taxom |
| Grandjeanicidae Kethley, 1977 | | 0 | Species | Taxom |
| Grandoculidae Penney, 2011 | | 1 | Species | Taxom |
| Granuloppiidae Balogh, 1983 | | 11 | Species | Taxom |
| Guanolichidae Fain, 1968 | | 3 | Species | Taxom |
| Guasiniidae Gonzalez-Sponga, 1997 | | 3 | Species | Taxom |
| Gustaviidae Oudemans, 1900 | | 3 | Species | Taxom |
| Gymnobisiidae Beier, 1947 | | 11 | Species | Taxom |
| Gymnodamaeidae Grandjean, 1954 | | 34 | Species | Taxom |
| Hadruridae Stahnke, 1974 | | 14 | Species | Taxom |
| Haemogamasidae Oudemans, 1939 | | 0 | Species | Taxom |
| Hahniidae Bertkau, 1878 | Dwarf sheet spiders | 116 | Species | Taxom |
| Halacaridae Murray, 1877 | Sea mites | 220 | Species | Taxom |
| Halarachnidae Oudemans, 1906 | | 12 | Species | Taxom |
| Halolaelapidae Karg, 1965 | | 7 | Species | Taxom |
| Halonoproctidae Pocock, 1901 | | 2 | Species | Taxom |
| Hammeriellidae Paschoal, 1989 | | 0 | Species | Taxom |
| Haplochthoniidae Van der Hammen, 1959 | | 5 | Species | Taxom |
| Haplozetidae Grandjean, 1936 | | 112 | Species | Taxom |
| Harpirhynchidae Dubinin, 1957 | | 83 | Species | Taxom |
| Hemileiidae (J. & P. Balogh, 1984) | | 48 | Species | Taxom |
| Hemisarcoptidae Oudemans, 1904 | | 6 | Species | Taxom |
| Hemiscorpiidae Pocock, 1893 | Longtail rock scorpions | 1 | Species | Taxom |
| Hermanniellidae Grandjean, 1934 | | 28 | Species | Taxom |
| Hermanniidae Sellnick, 1928 | | 20 | Species | Taxom |
| Hersiliidae Thorell, 1870 | Hersiliids | 35 | Species | Taxom |
| Hesperolpiidae Chamberlin, 1930 | | 38 | Species | Taxom |
| Heterobelbidae Balogh, 1961 | | 9 | Species | Taxom |
| Heterocheylidae Trägårdh, 1950 | | 1 | Species | Taxom |
| Heterocoptidae Fain, 1967 | | 1 | Species | Taxom |
| Heterotarbidae Petrunkevitch, 1913 | | 1 | Species | Taxom |
| Heterozerconidae Berlese, 1892 | | 3 | Species | Taxom |
| Hexathelidae Simon, 1892 | Australian funnelweb spiders | 18 | Species | Taxom |
| Hexisopodidae Karsch, 1879 | | 1 | Species | Taxom |
| Histiostomatidae Berlese, 1897 | | 127 | Species | Taxom |
| Homalonychidae Simon, 1893 | Dusty desert spiders | 2 | Species | Taxom |
| Homocaligidae Wood, 1969 | | 1 | Species | Taxom |
| Hoplomegistidae | | 0 | Species | Taxom |
| Hormuridae Laurie, 1896 | | 19 | Species | Taxom |
| Hubbardiidae Cook, 1899 | Hubbardiid shorttailed whipscorpions | 285 | Species | Taxom |
| Humerobatidae Grandjean, 1970 | | 14 | Species | Taxom |
| Hungarobelbidae (Miko & Travé, 1996) | | 2 | Species | Taxom |
| Hungarohydracaridae Motas & Tana..., 1959 | | 1 | Species | Taxom |
| Huttoniidae Simon, 1893 | Huttoniid spiders | 1 | Species | Taxom |
| Hyadesiidae Halbert, 1915 | | 16 | Species | Taxom |
| Hydrachnidae Leach, 1815 | | 38 | Species | Taxom |
| Hydrodromidae Viets, 1936 | | 4 | Species | Taxom |
| Hydrovolziidae Thor, 1905 | | 2 | Species | Taxom |
| Hydrozetidae Grandjean, 1954 | | 18 | Species | Taxom |
| Hydryphantidae Piersig, 1896 | | 81 | Species | Taxom |
| Hygrobatidae Koch, 1842 | | 198 | Species | Taxom |
| Hypochilidae Marx, 1888 | Lampshade spiders | 11 | Species | Taxom |
| Hypochthoniidae Berlese, 1910 | | 12 | Species | Taxom |
| Hypoderatidae (Murray, 1877) | | 14 | Species | Taxom |
| Hypoderidae Murray, 1877 | | 14 | Species | Taxom |
| Icaleptidae Kury & Pérez, 2002 | | 2 | Species | Taxom |
| Ichthyostomatogasteridae (Sellnick, 1953) | | 0 | Species | Taxom |
| Ideoroncidae Chamberlin, 1930 | | 53 | Species | Taxom |
| Idiopidae Simon, 1892 | Armored trapdoor spiders | 59 | Species | Taxom |
| Iolinidae Pritchard, 1956 | | 11 | Species | Taxom |
| Ischyropsalididae Simon, 1879 | | 8 | Species | Taxom |
| Isobuthidae Petrunkevitch, 1913 | | 2 | Species | Taxom |
| Ixodidae C. L. Koch, 1844 | Hard Tick | 150 | Species | Taxom |
| Ixodorhynchidae Ewing, 1923 | | 12 | Species | Taxom |
| Johnstonianidae Thor, 1935 | | 3 | Species | Taxom |
| Karschiidae Walter, 1889 | | 1 | Species | Taxom |
| Kimulidae Pérez Gonzal..., 2007 | | 34 | Species | Taxom |
| Klinckowstroemiidae Trägårdh, 1950 | | 21 | Species | Taxom |
| Knemidokoptidae (Lavoipierre ..., 1951) | | 3 | Species | Taxom |
| Kodiakellidae Hammer, 1967 | | 1 | Species | Taxom |
| Kramerellidae Gaud & Mouchet, 1961 | | 1 | Species | Taxom |
| Kreischeriidae Haase, 1890 | | 2 | Species | Taxom |
| Krendowskiidae Viets, 1926 | | 32 | Species | Taxom |
| Kronoscorpionidae Kjellesvig-W..., 1986 | | 1 | Species | Taxom |
| Kustarachnidae Petrunkevitch, 1949 | | 2 | Species | Taxom |
| Kytoditidae (Oudemans, 1908) | | 2 | Species | Taxom |
| Labidostommatidae Oudemans, 1904 | | 29 | Species | Taxom |
| Labriscorpionidae (Kjellesvig-W..., 1986) | | 1 | Species | Taxom |
| Laelapidae Berlese, 1892 | | 281 | Species | Taxom |
| Laelaptidae (Berlese, 1892) | | 1 | Species | Taxom |
| Laelaptonyssidae Womersley, 1956 | | 1 | Species | Taxom |
| Lagonomegopidae Eskov & Wund..., 1995 | | 1 | Species | Taxom |
| Lamellareidae Balogh, 1972 | | 2 | Species | Taxom |
| Laminosioptidae Vitzthum, 1931 | | 6 | Species | Taxom |
| Lamponidae Simon, 1893 | White-tailed spiders | 6 | Species | Taxom |
| Larcidae Harvey, 1992 | | 16 | Species | Taxom |
| Lardoglyphidae Oudemans, 1927 | | 5 | Species | Taxom |
| Larvamimidae Elzinga, 1993 | | 3 | Species | Taxom |
| Laversiidae Cook, 1955 | | 1 | Species | Taxom |
| Lebertiidae Thor, 1900 | | 13 | Species | Taxom |
| Leeuwenhoekiidae Womersley, 1944 | Chigger mites | 115 | Species | Taxom |
| Lemurnyssidae Fain, 1957 | | 0 | Species | Taxom |
| Leptolaelapidae Karg, 1978 | | 3 | Species | Taxom |
| Leptonetidae Simon, 1890 | Cave spiders | 96 | Species | Taxom |
| Liacaridae Sellnick, 1928 | | 50 | Species | Taxom |
| Licneremaeidae Grandjean, 1931 | | 11 | Species | Taxom |
| Licnobelbidae (Grandjean, 1965) | | 1 | Species | Taxom |
| Licnodamaeidae (Grandjean, 1954) | | 10 | Species | Taxom |
| Liebstadiidae J. & P. Balogh, 1984 | | 19 | Species | Taxom |
| Limnesiidae Thor, 1900 | | 164 | Species | Taxom |
| Limnocharidae Grube, 1859 | | 10 | Species | Taxom |
| Limnozetidae Thor, 1937 | | 12 | Species | Taxom |
| Linotetranidae Baker & Prit..., 1953 | | 1 | Species | Taxom |
| Linyphiidae Blackwall, 1859 | Dwarf spiders | 1957 | Species | Taxom |
| Liocranidae Simon, 1897 | Liocranid sac spiders | 32 | Species | Taxom |
| Liodidae Grandjean, 1954 | Round fungus beetle | 4 | Species | Taxom |
| Lissomartidae Dunlop, 1995 | | 2 | Species | Taxom |
| Listrophoridae Mégnin & Tro..., 1884 | | 107 | Species | Taxom |
| Listropsoralgidae Fain, 1965 | | 11 | Species | Taxom |
| Lobalgidae Fain, 1965 | | 9 | Species | Taxom |
| Lohmanniidae Berlese, 1916 | | 62 | Species | Taxom |
| Lordalychidae Grandjean, 1939 | | 1 | Species | Taxom |
| Lycosidae Lehtinen & H..., 1979 | Ground Spiders | 812 | Species | Taxom |
| Lyroppiidae Balogh, 1983 | | 4 | Species | Taxom |
| Machadobelbidae Balogh, 1972 | | 3 | Species | Taxom |
| Machuellidae Balogh, 1983 | | 2 | Species | Taxom |
| Macrochelidae Vitzthum, 1930 | | 87 | Species | Taxom |
| Macrodinychidae Hirschmann, 1979 | | 5 | Species | Taxom |
| Macronyssidae Oudemans, 1936 | Macronyssid Mites | 94 | Species | Taxom |
| Malaconothridae Berlese, 1916 | | 76 | Species | Taxom |
| Malkaridae Davies, 1980 | Malkarids | 1 | Species | Taxom |
| Maudheimiidae J. & P. Balogh, 1984 | | 2 | Species | Taxom |
| Mazoniidae Petrunkevitch, 1913 | | 3 | Species | Taxom |
| Mecicobothriidae Holmberg, 1882 | Dwarf tarantula | 13 | Species | Taxom |
| Mecognathidae Gerson & Walter, 1998 | | 1 | Species | Taxom |
| Mecysmaucheniidae Simon, 1895 | Mecysmaucheniid spiders | 24 | Species | Taxom |
| Megacelaenopsidae Funk, 1975 | | 1 | Species | Taxom |
| Megalolaelapidae | | 0 | Species | Taxom |
| Megisthanidae Berlese, 1914 | | 1 | Species | Taxom |
| Melicharidae (Hirschmann, 1962) | | 108 | Species | Taxom |
| Meliponocoptidae Fain & Rosa, 1983 | | 4 | Species | Taxom |
| Menthidae J.C. Chamberlin, 1930 | | 6 | Species | Taxom |
| Mesoplophoridae Ewing, 1917 | | 27 | Species | Taxom |
| Metagynuridae Baker & Wharton, 1952 | | 5 | Species | Taxom |
| Micreremidae Grandjean, 1954 | | 9 | Species | Taxom |
| Microdispidae Cross, 1965 | | 4 | Species | Taxom |
| Microgyniidae Trägårdh, 1942 | | 3 | Species | Taxom |
| Micropholcommatidae Hickman, 1943 | Micropholcommatid spiders | 7 | Species | Taxom |
| Micropsammidae Coineau & Th..., 1983 | | 0 | Species | Taxom |
| Microstigmatidae Raven & Plat..., 1981 | Microstigmatid spiders | 25 | Species | Taxom |
| Microtegeidae Balogh, 1972 | | 10 | Species | Taxom |
| Microtrombidiidae Womersley, 1936 | Micro velvet mites | 27 | Species | Taxom |
| Microzetidae Grandjean, 1936 | | 127 | Species | Taxom |
| Mideidae Thor, 1911 | | 2 | Species | Taxom |
| Mideopsidae Koenike, 1910 | | 56 | Species | Taxom |
| Migidae Simon, 1892 | Tree trapdoor spiders | 17 | Species | Taxom |
| Mimetidae Simon, 1881 | Pirate spider | 88 | Species | Taxom |
| Miturgidae Simon, 1885 | Long-legged sac spiders | 124 | Species | Taxom |
| Mochlozetidae Grandjean, 1960 | | 42 | Species | Taxom |
| Momoniidae Viets, 1926 | | 20 | Species | Taxom |
| Monoscutidae (Forster, 1948) | | 1 | Species | Taxom |
| Multoribulidae Balogh, 1972 | | 1 | Species | Taxom |
| Mummuciidae Mello-Leitão, 1938 | | 39 | Species | Taxom |
| Myobiidae Megnin, 1877 | | 78 | Species | Taxom |
| Myocoptidae Gunther, 1942 | | 8 | Species | Taxom |
| Myrmecicultoridae | | 1 | Species | Taxom |
| Mysmenidae Petrunkevitch, 1928 | Dwarf cobweb spiders | 94 | Species | Taxom |
| Nanhermanniidae Sellnick, 1928 | | 20 | Species | Taxom |
| Nanorchestidae Luxton, 1984 | | 8 | Species | Taxom |
| Nehypochthoniidae Norton & Metz, 1980 | | 1 | Species | Taxom |
| Nemastomatidae Simon, 1872 | | 24 | Species | Taxom |
| Nemastomoididae Petrunkevitch, 1955 | | 3 | Species | Taxom |
| Nematalycidae Strenzke, 1954 | | 4 | Species | Taxom |
| Nemesiidae Simon, 1892 | Tube Trapdoor Spiders | 26 | Species | Taxom |
| Nenteriidae Hirschmann, 1979 | | 53 | Species | Taxom |
| Neoacaridae (Motas & Tana..., 1947) | | 15 | Species | Taxom |
| Neobisiidae Chamberlin, 1930 | | 93 | Species | Taxom |
| Neogoveidae Shear, 1980 | | 21 | Species | Taxom |
| Neoliodidae (Sellnick, 1928) | | 18 | Species | Taxom |
| Neopilionidae Lawrence, 1931 | | 9 | Species | Taxom |
| Neopygmephoridae Cross, 1965 | | 11 | Species | Taxom |
| Neothrombiidae Feider, 1959 | | 2 | Species | Taxom |
| Neothyridae Lehtinen, 1981 | | 5 | Species | Taxom |
| Neotrombidiidae Feider, 1955 | | 1 | Species | Taxom |
| Nesticidae Simon, 1894 | Cave cobweb spider | 91 | Species | Taxom |
| Nicodamidae Simon, 1898 | Nicodamid spiders | 6 | Species | Taxom |
| Niphocepheidae Travé, 1959 | | 1 | Species | Taxom |
| Nodocepheidae Piffl, 1972 | | 4 | Species | Taxom |
| Nomoclastidae Roewer, 1943 | | 18 | Species | Taxom |
| Nosybeidae Mahunka, 1993 | | 1 | Species | Taxom |
| Nosybelbidae Mahunka, 1994 | | 35 | Species | Taxom |
| Nothridae Berlese, 1896 | | 43 | Species | Taxom |
| Ochyroceratidae Fage, 1912 | Midget ground weaver | 103 | Species | Taxom |
| Oecobiidae Blackwall, 1862 | Disc web spider | 26 | Species | Taxom |
| Oehserchestidae Kethley, 1977 | | 2 | Species | Taxom |
| Ogoveidae Shear, 1980 | | 7 | Species | Taxom |
| Ologamasidae Ryke, 1962 | | 197 | Species | Taxom |
| Olpiidae Banks, 1895 | | 56 | Species | Taxom |
| Omartacaridae Cook, 1963 | | 8 | Species | Taxom |
| Oonopidae Simon, 1890 | Dwarf Cell Spiders | 1200 | Species | Taxom |
| Opilioacaridae With, 1902 | | 37 | Species | Taxom |
| Opiliotarbidae Petrunkevitch, 1945 | | 1 | Species | Taxom |
| Oplitidae Johnston, 1968 | | 11 | Species | Taxom |
| Oppiidae Sellnick, 1937 | | 354 | Species | Taxom |
| Opsieobuthidae (Kjellesvig-W..., 1986) | | 1 | Species | Taxom |
| Oribatellidae Jacot, 1925 | | 102 | Species | Taxom |
| Oribatidae | | 1 | Species | Taxom |
| Oribatulidae Thor, 1929 | | 86 | Species | Taxom |
| Oribellidae (Kunst, 1971) | | 11 | Species | Taxom |
| Oribotritiidae Grandjean, 1954 | | 76 | Species | Taxom |
| Oripodidae Jacot, 1925 | | 61 | Species | Taxom |
| Orsolobidae Cooke, 1965 | Orsolobid spiders | 45 | Species | Taxom |
| Otocepheidae Balogh, 1961 | | 38 | Species | Taxom |
| Otopheidomenidae Treat, 1955 | | 10 | Species | Taxom |
| Oxidae Viets, 1926 | | 36 | Species | Taxom |
| Oxyopidae Thorell, 1870 | Lynx spiders | 130 | Species | Taxom |
| Pachylaelapidae Berlese, 1913 | | 18 | Species | Taxom |
| Palaeacaridae Grandjean, 1932 | | 1 | Species | Taxom |
| Palaeobuthidae Kjellesvig-W..., 1986 | | 1 | Species | Taxom |
| Palaeocharinidae Hirst, 1923 | | 8 | Species | Taxom |
| Palaeophonidae Thorell & Li..., 1885 | | 2 | Species | Taxom |
| Palaeopisthacanthidae Kjellesvig-W..., 1986 | | 1 | Species | Taxom |
| Palpimanidae Thorell, 1870 | Palp-footed spiders | 80 | Species | Taxom |
| Paracharontidae Weygoldt, 1996 | | 3 | Species | Taxom |
| Paraisobuthidae Kjellesvig-W..., 1986 | | 1 | Species | Taxom |
| Parakalummidae Grandjean, 1936 | | 22 | Species | Taxom |
| Paramegistidae Trägårdh, 1946 | | 1 | Species | Taxom |
| Paranonychidae (Briggs, 1971) | | 24 | Species | Taxom |
| Parantennulidae Willmann, 1940 | | 1 | Species | Taxom |
| Pararchaeidae Forster & Pl..., 1984 | Pararchaeid spiders | 1 | Species | Taxom |
| Parasitidae Oudemans, 1901 | Beetle Mites | 75 | Species | Taxom |
| Paratropididae Simon, 1889 | Bald-legged spiders | 41 | Species | Taxom |
| Parattidae Petrunkevitch, 1922 | | 4 | Species | Taxom |
| Paratydeidae Baker, 1949 | | 7 | Species | Taxom |
| Parholaspididae Evans, 1956 | | 29 | Species | Taxom |
| Parhypochthoniidae Grandjean, 1932 | | 2 | Species | Taxom |
| Passalozetidae Grandjean, 1954 | | 9 | Species | Taxom |
| Pediculochelidae Lavoipierre, 1946 | | 2 | Species | Taxom |
| Peloppiidae Balogh, 1943 | | 7 | Species | Taxom |
| Pentanychidae Briggs, 1971 | | 5 | Species | Taxom |
| Penthaleidae Oudemans, 1931 | Earth Mites | 6 | Species | Taxom |
| Penthalodidae Strandtmann, 1964 | | 13 | Species | Taxom |
| Perlohmanniidae Grandjean, 1954 | | 3 | Species | Taxom |
| Pettalidae Simon, 1879 | | 4 | Species | Taxom |
| Phalangiidae Latreille, 1802 | Daddy-Long-Legs | 59 | Species | Taxom |
| Phalangodidae Simon, 1879 | | 142 | Species | Taxom |
| Phaulodinychidae (Berlese, 1917) | | 0 | Species | Taxom |
| Phenopelopidae Petrunkevitch, 1955 | | 35 | Species | Taxom |
| Pheroliodidae Paschoal, 1987 | | 34 | Species | Taxom |
| Philodanidae Kethley, 1977 | | 1 | Species | Taxom |
| Philodinidae Ehrenberg, 1838 | | 1 | Species | Taxom |
| Philodromidae Thorell, 1870 | False crab spiders | 267 | Species | Taxom |
| Pholcidae C. L. Koch, 1851 | Carpenter spider | 857 | Species | Taxom |
| Phrynichidae Simon, 1892 | | 5 | Species | Taxom |
| Phrynidae Blanchard, 1852 | | 118 | Species | Taxom |
| Phthiracaridae Perty, 1841 | | 411 | Species | Taxom |
| Phytoptidae Manson, 1970 | | 33 | Species | Taxom |
| Phytoseiidae Berlese, 1916 | Phytoseiid mites | 420 | Species | Taxom |
| Piersigiidae Oudemans, 1902 | | 2 | Species | Taxom |
| Pimoidae Wunderlich, 1986 | Pimoid spiders | 16 | Species | Taxom |
| Pionidae Thor, 1900 | | 117 | Species | Taxom |
| Pirnodidae Grandjean, 1956 | | 1 | Species | Taxom |
| Pisauridae Simon, 1890 | Big wolf spider | 101 | Species | Taxom |
| Plasmobatidae Grandjean, 1961 | | 17 | Species | Taxom |
| Plateremaeidae Trägårdh, 1931 | | 10 | Species | Taxom |
| Platyameridae Balogh & Balogh, 1983 | | 3 | Species | Taxom |
| Plectreuridae Simon, 1893 | Plectreurid spider | 33 | Species | Taxom |
| Pneumocoptidae Fain, 1957 | | 2 | Species | Taxom |
| Podapolipidae Husband, 1990 | | 55 | Species | Taxom |
| Podocinidae Berlese, 1913 | | 12 | Species | Taxom |
| Podoctidae Roewer, 1912 | | 3 | Species | Taxom |
| Podopterotegaeidae (Piffl, 1972) | | 1 | Species | Taxom |
| Poliocheridae Scudder, 1884 | | 3 | Species | Taxom |
| Polyaspidae (Berlese, 1913) | | 1 | Species | Taxom |
| Polyaspididae Berlese, 1913 | | 33 | Species | Taxom |
| Pomerantziidae Baker, 1949 | | 4 | Species | Taxom |
| Pontarachnidae Koenike, 1910 | | 4 | Species | Taxom |
| Praearcturidae Kjellesvig-W..., 1986 | | 0 | Species | Taxom |
| Proctophyllodidae Trouessart &..., 1884 | | 105 | Species | Taxom |
| Prodidomidae (Simon, 1882) | Long-spinnered ground spiders | 0 | Species | Taxom |
| Prokoeneniidae Condé, 1991 | | 3 | Species | Taxom |
| Proscorpiidae Scudder, 1885 | | 4 | Species | Taxom |
| Proteonematalycidae Kethley, 1989 | | 1 | Species | Taxom |
| Proterorhagiidae Lindquist & ..., 1991 | | 1 | Species | Taxom |
| Protochthoniidae Norton, 1988 | | 1 | Species | Taxom |
| Protodinychidae Evans, 1957 | | 1 | Species | Taxom |
| Protoplophoridae (Ewing, 1917) | | 11 | Species | Taxom |
| Protoribatidae J. & P. Balogh, 1984 | | 33 | Species | Taxom |
| Protoschizomidae Rowland, 1975 | | 17 | Species | Taxom |
| Protosolpugidae Petrunkevitch, 1953 | | 1 | Species | Taxom |
| Psammochthoniidae Fuangarworn ..., 2013 | | 1 | Species | Taxom |
| Pseudocheylidae Oudemans, 1909 | | 5 | Species | Taxom |
| Pseudochiridiidae Chamberlin, 1923 | | 2 | Species | Taxom |
| Pseudogarypidae J.C. Chamberlin, 1923 | | 6 | Species | Taxom |
| Pseudoppiidae (Mahunka, 1975) | | 3 | Species | Taxom |
| Psoralgidae Oudemans, 1908 | | 10 | Species | Taxom |
| Psorergatidae Womersley, 1941 | | 25 | Species | Taxom |
| Psoroptidae Hering, 1838 | Scab mites | 8 | Species | Taxom |
| Psoroptoididae Gaud, 1958 | | 9 | Species | Taxom |
| Pterobatidae (Balogh & Mah..., 1977) | | 1 | Species | Taxom |
| Pterolichidae Trouessart, 1899 | | 86 | Species | Taxom |
| Pteronyssidae Oudemans, 1941 | | 18 | Species | Taxom |
| Pterygosomatidae Womersley, 1941 | | 13 | Species | Taxom |
| Ptiloxenidae Gaud, 1982 | | 3 | Species | Taxom |
| Ptyssalgidae Atyeo & Gaud, 1979 | | 0 | Species | Taxom |
| Punctoribatidae Thor, 1937 | | 45 | Species | Taxom |
| Pyemotidae Newport, 1850 | | 7 | Species | Taxom |
| Pygmephoridae Krczal, 1964 | | 36 | Species | Taxom |
| Pyramidopidae Starega, 1992 | | 2 | Species | Taxom |
| Pyroglyphidae Cunliffe, 1958 | Dust mites | 32 | Species | Taxom |
| Pyrosejidae Lindquist & ..., 1993 | | 0 | Species | Taxom |
| Quadroppiidae Balogh, 1983 | | 11 | Species | Taxom |
| Raillietiidae Vitzthum, 1943 | | 4 | Species | Taxom |
| Raphignathidae Kramer, 1877 | | 10 | Species | Taxom |
| Rectijanuidae Gaud, 1961 | | 0 | Species | Taxom |
| Rhagidiidae Zacharda, 1980 | | 68 | Species | Taxom |
| Rhagodidae Pocock, 1897 | | 1 | Species | Taxom |
| Rhinonyssidae Trouessart, 1895 | | 202 | Species | Taxom |
| Rhodacaridae Oudemans, 1902 | | 67 | Species | Taxom |
| Rhynchohydracaridae Lundblad, 1936 | | 1 | Species | Taxom |
| Rhynchoribatidae Balogh, 1961 | | 20 | Species | Taxom |
| Rhyncoptidae Lawrence, 1956 | | 3 | Species | Taxom |
| Ricinoididae Ewing, 1929 | Hooded tickspiders | 91 | Species | Taxom |
| Rioppiidae Balogh & Mah..., 1977 | | 2 | Species | Taxom |
| Rosensteiniidae Cooreman, 1954 | | 16 | Species | Taxom |
| Sabaconidae Dresco, 1970 | Sabaconid Harvestmen | 14 | Species | Taxom |
| Salticidae Blackwall, 1842 | Jumping Spider | 3329 | Species | Taxom |
| Salvidae Özdikmen, 2008 | | 1 | Species | Taxom |
| Samoidae Sørensen, 1886 | | 42 | Species | Taxom |
| Sarcoptidae Megnin, 1877 | Itch mites | 30 | Species | Taxom |
| Scheloribatidae Jacot, 1935 | | 112 | Species | Taxom |
| Schizogyniidae Trägårdh, 1950 | | 1 | Species | Taxom |
| Sclerosomatidae Simon, 1879 | Sclerosomatid Harvestmen | 464 | Species | Taxom |
| Scorpionidae Pierre André..., 1802 | Largeclaw scorpions | 156 | Species | Taxom |
| Scutacaridae Paoli, 1911 | | 66 | Species | Taxom |
| Scutoverticidae Grandjean, 1954 | | 16 | Species | Taxom |
| Scytodidae Blackwall, 1864 | Glue spitter | 153 | Species | Taxom |
| Segestriidae Simon, 1893 | Six-eyed Spiders | 59 | Species | Taxom |
| Sejidae Berlese, 1885 | | 14 | Species | Taxom |
| Selenopidae Simon, 1897 | Flatties | 101 | Species | Taxom |
| Selenoribatidae Schuster, 1963 | | 17 | Species | Taxom |
| Senoculidae Simon, 1890 | Senoculid spiders | 31 | Species | Taxom |
| Sicariidae Keyserling, 1880 | Brown recluse spiders | 155 | Species | Taxom |
| Sironidae Simon, 1879 | | 11 | Species | Taxom |
| Siteroptidae Martin, 1978 | Siteroptid mites | 17 | Species | Taxom |
| Smarididae Kramer, 1878 | | 24 | Species | Taxom |
| Solpugidae Leach, 1815 | | 3 | Species | Taxom |
| Sparassidae Bertkau, 1872 | Giant crab spiders | 424 | Species | Taxom |
| Spelaeorhynchidae Oudemans, 1902 | | 9 | Species | Taxom |
| Sperchontidae Thor, 1900 | | 46 | Species | Taxom |
| Sphaerochthoniidae Grandjean, 1947 | | 8 | Species | Taxom |
| Sphaerolichidae Berlese, 1913 | | 1 | Species | Taxom |
| Spinturnicidae Oudemans, 1902 | | 54 | Species | Taxom |
| Staurobatidae Grandjean, 1966 | | 2 | Species | Taxom |
| Steganacaridae (Niedbała, 1986) | | 20 | Species | Taxom |
| Sternophoridae J.C. Chamberlin, 1923 | | 8 | Species | Taxom |
| Sternoppiidae Balogh & Mah..., 1969 | | 14 | Species | Taxom |
| Stigmaeidae Wood, 1967 | | 165 | Species | Taxom |
| Stigmocheylidae (Kethley, 1990) | | 2 | Species | Taxom |
| Stiphidiidae Dalmas, 1917 | Sheetweb spiders | 5 | Species | Taxom |
| Stoermeroscorpionidae (Kjellesvig-W..., 1986) | | 1 | Species | Taxom |
| Stygnidae Simon, 1879 | | 84 | Species | Taxom |
| Stygnommatidae Roewer, 1923 | | 28 | Species | Taxom |
| Stygnopsidae Sørensen, 1932 | | 29 | Species | Taxom |
| Stygothrombiidae Thor, 1935 | | 3 | Species | Taxom |
| Suctobelbidae Jacot, 1938 | | 124 | Species | Taxom |
| Suidasiidae Hughes, 1948 | | 6 | Species | Taxom |
| Superstitioniidae Stahnke, 1940 | | 19 | Species | Taxom |
| Syarinidae Chamberlin, 1930 | | 63 | Species | Taxom |
| Symphytognathidae Hickman, 1931 | Dwarf orb-weavers | 26 | Species | Taxom |
| Synichotritiidae Walker, 1965 | | 8 | Species | Taxom |
| Synotaxidae Simon, 1894 | Synotaxid spiders | 19 | Species | Taxom |
| Syringobiidae Trouessart, 1897 | | 20 | Species | Taxom |
| Syringophilidae Lavoipierre, 1953 | Quill mites | 182 | Species | Taxom |
| Tanaupodidae Thor, 1935 | | 4 | Species | Taxom |
| Taracidae Schönhofer, 2013 | | 24 | Species | Taxom |
| Tarsocheylidae Berlese, 1904 | | 4 | Species | Taxom |
| Tarsonemidae Kramer, 1877 | Tarsonemid mites | 170 | Species | Taxom |
| Tectocepheidae Grandjean, 1954 | | 11 | Species | Taxom |
| Tegeocranellidae P. Balogh, 1987 | | 7 | Species | Taxom |
| Tegoribatidae Grandjean, 1954 | | 17 | Species | Taxom |
| Telemidae Fage, 1913 | Long-legged cave spider | 9 | Species | Taxom |
| Telmatoscorpionidae Kjellesvig-W..., 1986 | | 1 | Species | Taxom |
| Teneriffiidae Thor, 1911 | | 6 | Species | Taxom |
| Tengellidae (Dahl, 1908) | Tengellid spiders | 52 | Species | Taxom |
| Tenuialidae Jacot, 1929 | | 5 | Species | Taxom |
| Tenuipalpidae Berlese, 1913 | False spider mites | 403 | Species | Taxom |
| Teratoppiidae Balogh, 1983 | | 12 | Species | Taxom |
| Terpnacaridae Grandjean, 1939 | | 1 | Species | Taxom |
| Tetrablemmidae O. P-Cambridge, 1873 | Armored spider | 27 | Species | Taxom |
| Tetracondylidae Aoki, 1961 | | 1 | Species | Taxom |
| Tetragnathidae Menge, 1866 | Elongated Orb Weavers | 526 | Species | Taxom |
| Tetranychidae Donnadieu, 1875 | Spider mites | 607 | Species | Taxom |
| Teutoniidae Koenike, 1910 | | 1 | Species | Taxom |
| Thelyphonidae Lucas, 1835 | | 50 | Species | Taxom |
| Theraphosidae Thorell, 1870 | Bird-eating spiders | 1088 | Species | Taxom |
| Theridiidae Sundevall, 1833 | Cobweb And Widow Spiders | 1595 | Species | Taxom |
| Theridiosomatidae Simon, 1881 | Ray orbweavers | 77 | Species | Taxom |
| Thermacaridae Sokolow, 1927 | | 3 | Species | Taxom |
| Thomisidae Sundevall, 1833 | Crab Spider | 823 | Species | Taxom |
| Thyrisomidae Grandjean, 1953 | | 12 | Species | Taxom |
| Titanoecidae Lehtinen, 1967 | Rock Weavers | 29 | Species | Taxom |
| Torrenticolidae Thor, 1902 | Torrent Mites | 99 | Species | Taxom |
| Trachelidae Simon, 1897 | | 4 | Species | Taxom |
| Trachytidae Tragärdh, 1938 | | 3 | Species | Taxom |
| Trachyuropodidae Kramer, 1881 | | 115 | Species | Taxom |
| Travuniidae Absolon & Kr..., 1932 | | 18 | Species | Taxom |
| Trechaleidae Simon, 1890 | Trechaleid spiders | 137 | Species | Taxom |
| Trematuridae Berlese, 1917 | | 192 | Species | Taxom |
| Trhypochthoniidae Willmann, 1931 | | 35 | Species | Taxom |
| Triaenonychidae Sörensen, 1886 | | 44 | Species | Taxom |
| Trichthoniidae (Lee, 1982) | | 3 | Species | Taxom |
| Tridenchthoniidae Balzan, 1892 | | 1 | Species | Taxom |
| Trigonomartidae Petrunkevitch, 1949 | | 2 | Species | Taxom |
| Trigonotarbidae Petrunkevitch, 1949 | | 2 | Species | Taxom |
| Trigonuropodidae Hirschmann, 1979 | | 12 | Species | Taxom |
| Trionyxellidae Roewer, 1912 | | 2 | Species | Taxom |
| Triophytydeidae | | 0 | Species | Taxom |
| Triplogyniidae Funk, 1977 | | 1 | Species | Taxom |
| Trizetidae Ewing, 1917 | | 1 | Species | Taxom |
| Trochanteriidae Karsch, 1879 | Flat spiders | 16 | Species | Taxom |
| Trogloraptoridae Griswold, A..., 2012 | | 1 | Species | Taxom |
| Trogulidae Sundevall, 1833 | | 4 | Species | Taxom |
| Trombellidae Thor, 1935 | | 1 | Species | Taxom |
| Trombiculidae Ewing, 1929 | Chigger mites | 672 | Species | Taxom |
| Trombidiidae Leach, 1815 | Beer Bahuti | 34 | Species | Taxom |
| Trouessartiidae Gaud, 1957 | | 14 | Species | Taxom |
| Tubulozetidae P. Balogh, 1989 | | 1 | Species | Taxom |
| Tuckerellidae Baker & Prit..., 1953 | Peacock mites | 4 | Species | Taxom |
| Turbinoptidae Fain, 1957 | | 9 | Species | Taxom |
| Tydeidae Kramer, 1877 | Tydeid mites | 32 | Species | Taxom |
| Uloboridae Thorell, 1869 | Cribellate orb weavers | 121 | Species | Taxom |
| Unduloribatidae Kunst, 1971 | | 2 | Species | Taxom |
| Unionicolidae Oudemans, 1909 | | 247 | Species | Taxom |
| Uroactiniidae Hirschmann &..., 1964 | | 0 | Species | Taxom |
| Urodinychidae Berlese, 1917 | | 81 | Species | Taxom |
| Uropodellidae (Camin, 1955) | | 3 | Species | Taxom |
| Uropodidae Kramer, 1881 | | 331 | Species | Taxom |
| Vaejovidae Thorell, 1876 | | 327 | Species | Taxom |
| Varroidae Delfinado & ..., 1974 | | 4 | Species | Taxom |
| Veigaiidae Oudemans, 1939 | | 24 | Species | Taxom |
| Wettinidae Cook, 1956 | | 3 | Species | Taxom |
| Winterschmidtiidae Oudemans, 1923 | | 68 | Species | Taxom |
| Withiidae Chamberlin, 1931 | | 68 | Species | Taxom |
| Xenillidae Woolley & Hi..., 1966 | | 53 | Species | Taxom |
| Xenocaligonellididae González, 1978 | | 2 | Species | Taxom |
| Xolalgidae Dubinin, 1953 | | 19 | Species | Taxom |
| Xylobatidae J. Balogh & ..., 1984 | | 2 | Species | Taxom |
| Zalmoxidae (Sörensen, 1886) | | 144 | Species | Taxom |
| Zerconidae Berlese, 1892 | | 13 | Species | Taxom |
| Zetomimidae Shaldybina, 1966 | | 1 | Species | Taxom |
| Zetomotrichidae Grandjean, 1934 | | 7 | Species | Taxom |
| Zetorchestidae Michael, 1898 | | 3 | Species | Taxom |
| Zodariidae Thorell, 1881 | Ant spiders | 209 | Species | Taxom |
| Zoridae F. O. P-Camb..., 1893 | Wandering Spiders | 40 | Species | Taxom |
| Zorocratidae (Dahl, 1913) | Zorocratid spider | 33 | Species | Taxom |
| Zoropsidae Bertkau, 1882 | False Huntsman Spiders | 3 | Species | Taxom |
