Abacoproeces Simon, 1884 (extant flag source)
Aberdaria Holm, 1962 (extant flag source)
Abiskoa Saaristo & Tanasevitch, 2000 (extant flag source)
Ablabesmyia Johannsen, 1905 (habitat flag source)
Ablemma Roewer, 1963 (extant flag source)
Abracadabrella Zabka, 1991 (extant flag source)
Acacesia Simon, 1895 (extant flag source)
Acantharachne Tullgren, 1910 (extant flag source)
Acantheis Thorell, 1891 (extant flag source)
Acanthepeira Marx, 1883 (extant flag source)
Acanthicochernes Beier, 1964 (extant flag source)
Acanthobatis accepted as Anacanthobatis von Bonde & Swart, 1923 (source of synonymy)
Acanthoceto Mello-Leitão, 1944 (extant flag source)
Acanthocladium Mitten, 1878 (current name source)
Acanthocreagris Mahnert, 1974 (extant flag source)
Acanthocymbium Ott & Lise, 1997 (extant flag source)
Acanthoderus Gray, 1835 (current name source)
Acanthodium Mitten, 1868 (current name source)
Acanthogonatus Karsch, 1880 (extant flag source)
Acantholycosa Dahl, 1908 (extant flag source)
Acanthomarginata S.N. Naumova ex N.I. Umnova in N.I. Umnova & E.K. Vanderflit in V.K. Golubzov, 1971 † (current name source)
Acanthopelma F.O. Pickard-Cambridge, 1897 (extant flag source)
Acanthoscurria Ausserer, 1871 (extant flag source)
Acanthosphaera S.N. Naumova, 1968 † (source of synonymy)
Acanthoxyla Uvarov, 1944 (current name source)
Acanthus Linnaeus, 1753 (habitat flag source)
Acartauchenius Simon, 1884 (extant flag source)
Acarus Linnaeus, 1758 (extant flag source)
Acentroscelus Simon, 1886 (extant flag source)
Aceratias Brauer, 1902 accepted as Linophryne Collett, 1886 (habitat flag source)
Aceria Keifer, 1944 (extant flag source)
Achaea Hübner, 1823 (current name source)
Achaearanea Strand, 1929 (extant flag source)
Achaearyopa Barrion & Litsinger, 1995 (extant flag source)
Achaeta Vejdovský, 1878 (habitat flag source)
Acompse Koch, 1879 accepted as Bavia Simon, 1877 (extant flag source)
Acotyledon Oudemans, 1902 (extant flag source)
Acracanthostoma Mello-Leitão, 1918 (extant flag source)
Acragas Simon, 1900 (extant flag source)
Acritoscincus Wells & Wellington, 1985 (current name source)
Acroaspis Karsch, 1878 (extant flag source)
Acrobeles Von Linstow, 1887 (habitat flag source)
Acrobeloides Cobb, 1924 (habitat flag source)
Acrosomoides Simon, 1887 (extant flag source)
Acrum M.A. Fombella Blanco, 1977 † (current name source)
Actinacantha Simon, 1864 (extant flag source)
Actinopycnidium Krasil'nikov, 1962 (Approved Lists, 1980) (current name source)
Actinosoma Holmberg, 1883 (extant flag source)
Actinosporangium Krasil'nikov & Yuan, 1961 (Approved Lists, 1980) (current name source)
Actinotophasis A.R. Loeblich Jr. & E.R. Wicander, 1976 † (current name source)
Aculeobreda Caporiacco, 1955 accepted as Pachomius Peckham, 1896 (extant flag source)
Aculepeira Chamberlin & Ivie, 1942 (extant flag source)
Aculus Keifer, 1959 (extant flag source)
Acuminochernes Hoff, 1949 (extant flag source)
Acusilas Simon, 1895 (extant flag source)
Adara M.A. Fombella Blanco, 1977 † (current name source)
Adarve M.A. Fombella Blanco, 1977 † (current name source)
Adelocosa Gertsch, 1973 (extant flag source)
Adelonetria Millidge, 1991 (extant flag source)
Adelphochernes Beier, 1937 (extant flag source)
Adenopleura Macalister, 1872 (extant flag source)
Admestina Peckham, 1888 (extant flag source)
Admesturius Galiano, 1988 (extant flag source)
Adonea Simon, 1873 (extant flag source)
Adoxotoma Simon, 1909 (extant flag source)
Aducta Z.K. Fajzulina in Z.A. Akulcheva et al., 1981 † (current name source)
Aebutina Simon, 1892 (extant flag source)
Aelurillus Simon, 1885 (extant flag source)
Aelurostrongylus Cameron, 1927 (current name source)
Aenetus Herrich-Schäffer, 1856 (current name source)
Aequitriradites A. Delcourt & G. Sprumont, 1955 † (habitat flag source)
Aerea Urquhart, 1891 accepted as Arkys Walckenaer, 1836 (extant flag source)
Aethriscus Pocock, 1902 (extant flag source)
Aethrodiscus Strand, 1913 (extant flag source)
Aetrocantha Karsch, 1879 (extant flag source)
Afracantha Dahl, 1914 (extant flag source)
Afraflacilla Berland & Millot, 1941 (extant flag source)
Afrarchaea Forster & Platnick, 1984 (extant flag source)
Afribactrus Wunderlich in Wunderlich & Nicolai, 1994 (extant flag source)
Africactenus Hyatt, 1954 (extant flag source)
Afrobeata Caporiacco, 1941 (extant flag source)
Afroblemma Lehtinen, 1981 (extant flag source)
Afromynoglenes Merrett & Russell-Smith, 1996 (extant flag source)
Afroneta Holm, 1968 (extant flag source)
Afropisaura Blandin, 1976 (extant flag source)
Afrothyrsocnema Rohdendorf, 1963 (current name source)
Agalenatea Archer, 1951 (extant flag source)
Agalenocosa Mello-Leitão, 1944 (extant flag source)
Agassa Simon, 1901 accepted as Sassacus Peckham, 1895 (extant flag source)
Agathis R.A. Salisbury, 1807 (extant flag source)
Agathostichus Simon, 1897 accepted as Mastophora Holmberg, 1876 (extant flag source)
Agelista Simon, 1900 accepted as Titanattus Peckham, 1885 (extant flag source)
Aglaoctenus Tullgren, 1905 (extant flag source)
Agnyphantes Hull, 1932 (extant flag source)
Agobardus Keyserling, 1885 (extant flag source)
Agorius Simon, 1901 accepted as Agorius Thorell, 1877 (extant flag source)
Agriognatha O. Pickard-Cambridge, 1896 (extant flag source)
Agroeca Westring, 1861 (extant flag source)
Agyneta Hull, 1911 (extant flag source)
Aida Castelnau, 1875 accepted as Melanotaenia Gill, 1862 (habitat flag source)