[living organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Superkingdom Prokaryota Margulis 1974 nom. nud.
     Kingdom Archaea Woese et al. 1990 see Domain Archaea Woese et al. 1990 stat. inval.
       Phylum Euryarchaeota Garrity and Holt 2002 stat. inval. see Kingdom Methanobacteriati (Garrity and Holt 2023) Oren and Göker 2024
         1 Class Archaeoglobi Garrity and Holt 2002 [monotypic]
         2 Class Halobacteria Grant et al. 2002 [monotypic]
         3 Class Methanobacteria Boone 2002 [monotypic]
         4 Class Methanococci Boone 2002 [monotypic]
         5 Class "Methanomicrobia" Garrity et al. 2005 nom. inval.
         6 Class Methanopyri Garrity and Holt 2002 [monotypic]
         7 Class "Nanohaloarchaea" Narasingarao et al. 2012 nom. pro-inval.
         8 Class Thermococci Zillig and Reysenbach 2002 [monotypic]
         9 Class Thermoplasmata Reysenbach 2002 [monotypic]