Order Scorpiones Koch, 1837 - scorpions
   01 Family †Acanthoscorpioniidae Dunlop, Penney & Jekel, 2010, orth. inval. [monotypic] see Family Acanthoscorpionidae Kjellesvig-Waering, 1986
   02 Family Akravidae Levy, 2007 [monotypic]
   03 Family †Allobuthiscorpiidae Kjellesvig-Waering, 1986
   04 Family †Allopalaeophonidae Kjellesvig-Waering, 1986 [monotypic]
   05 Family †Anthracoscorpionidae Fritsch, 1904
   06 Family †Archaeobuthidae Lourenço, 2001 [monotypic]
   07 Family Bothriuridae Simon, 1880
   08 Family †Branchioscorpioniidae Dunlop, Penney & Jekel, 2010, orth. inval. [monotypic] see Family Branchioscorpionidae Kjellesvig-Waering, 1986
   09 Family Buthidae Koch, 1837
   10 Family †Buthiscorpiidae Kjellesvig-Waering, 1986 [monotypic]
   11 Family †Centromachidae Petrunkevitch, 1953
   12 Family Chactidae Pocock, 1893
   13 Family Chaerilidae Pocock, 1893
   14 Family †Chaerilobuthidae Lourenço & Beigel, 2011 [monotypic]
   15 Family †Cyclophthalmidae Thorell & Lindström, 1885 [monotypic]
   16 Family Diplocentridae Karsch, 1880
   17 Family †Dolichophoniidae Dunlop, Penney & Jekel, 2010, orth. inval. [monotypic] see Family Dolichophonidae Petrunkevitch, 1953
   18 Family †Eobuthidae Kjellesvig-Waering, 1986 [monotypic]
   19 Family †Eoctonidae Kjellesvig-Waering, 1986 [monotypic]
   20 Family †Eoscorpiidae Scudder, 1884
   21 Family Euscorpiidae Laurie, 1896
   22 Family †Gallioscorpionidae Lourenço & Gall, 2004 [monotypic]
   23 Family †Garnettiidae Dubinin, 1962 [monotypic]
   24 Family †Gigantoscorpionidae Kjellesvig-Waering, 1986
   25 Family †Heloscorpionidae Kjellesvig-Waering, 1986 [monotypic]
   26 Family Hemiscorpiidae Pocock, 1893 [monotypic]
   27 Family Heteroscorpionidae Kraepelin, 1905 [monotypic]
   28 Family Hormuridae Laurie, 1896
   29 Family †Isobuthidae Petrunkevitch, 1913
   30 Family Iuridae Thorell, 1876
   31 Family †Kronoscorpionidae Kjellesvig-Waering, 1986 [monotypic]
   32 Family †Loboarchaeoctonidae Kjellesvig-Waering, 1986 [monotypic]
   33 Family †Mazoniidae Petrunkevitch, 1913 [monotypic]
   34 Family †Mesophonidae Wills, 1910 [monotypic]
   35 Family †Microlabiidae Kjellesvig-Waering, 1986, orth. inval. [monotypic] see Family Microlabidae Kjellesvig-Waering, 1986
   36 Family †Palaeoburmesebuthidae Lourenço, 2015
   37 Family †Palaeobuthidae Kjellesvig-Waering, 1986 [monotypic]
   38 Family †Palaeoeuscorpidae Dunlop, Penney & Jekel, 2010, orth. inval. see Family Palaeoeuscorpiidae Lourenço, 2003
   39 Family †Palaeoscorpionidae Lehmann, 1944, orth. inval. [monotypic] see Family Palaeoscorpiidae Lehmann, 1944
   40 Family †Palaeophonidae Thorell & Lindström, 1885 [monotypic]
   41 Family †Palaeopisthacanthidae Kjellesvig-Waering, 1986
   42 Family †Palaeotrilineatidae Lourenço, 2012 [monotypic]
   43 Family †Paraisobuthidae Kjellesvig-Waering, 1986 [monotypic]
   44 Family †Pareobuthidae Kjellesvig-Waering, 1986 [monotypic]
   45 Family †Praearcturidae Kjellesvig-Waering, 1986 [monotypic]
   46 Family †Proscorpiidae Scudder, 1885
   47 Family †Protobuthidae Lourenço & Gall, 2004 [monotypic]
   48 Family †Protoischnuridae Carvalho & Lourenço, 2001
   49 Family Pseudochactidae Gromov, 1998
   50 Family †Scoloposcorpionidae Kjellesvig-Waering, 1986
   51 Family Scorpionidae Latreille, 1802
   52 Family Scorpiopidae Kraepelin, 1905
   53 Family †Spongiophonidae Kjellesvig-Waering, 1986 [monotypic]
   54 Family †Stenoscorpioniidae Dunlop, Penney & Jekel, 2010, orth. inval. [monotypic] see Family Stenoscorpionidae Kjellesvig-Waering, 1986
   55 Family †Sucinlourencoidae Rossi, 2015 [monotypic]
   56 Family Superstitioniidae Stahnke, 1940 [monotypic]
   57 Family †Telmatoscorpionidae Kjellesvig-Waering, 1986 [monotypic]
   58 Family Troglotayosicidae Lourenço, 1998
   59 Family Typhlochactidae Mitchell, 1968
   60 Family Urodacidae Pocock, 1893
   61 Family Vaejovidae Thorell, 1876
   62 Family †Waterstoniidae Kjellesvig-Waering, 1986 [monotypic]
   63 Family †Willsiscorpionidae Kjellesvig-Waering, 1986 [monotypic]
   64 Orthosternina Pocock, 1911 see Infraorder Orthosterni Pocock, 1911
   65 Genus †Compsoscorpius Petrunkevitch, 1949
   66 Genus †Brontoscorpio Kjellesvig-Waering, 1972, incertae sedis
   67 Genus †Eramoscorpius Waddington, Rudkin & Dunlop, 2015, incertae sedis
   68 Genus †Gondwanascorpio Gess, 2013, incertae sedis
   69 Genus †Gymnoscorpius Jeram, 1994, incertae sedis
   70 Genus †Hubeiscorpio Walossek, Li & Brauckmann, 1990, incertae sedis
   71 Genus †Liassoscorpionides Bode, 1951, incertae sedis
   72 Genus †Palaeomachus Pocock, 1911, incertae sedis
   73 Genus †Permomatveevia Dammann, 2017, incertae sedis
   74 Genus †Titanoscorpio Kjellesvig-Waering, 1986, incertae sedis
   75 Genus †Wattisonia Wills, 1960, incertae sedis