life
 see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
  
 Empire Eukaryota (Chatton, 1925)
 see Domain Eukaryota Chatton, 1925
    
 Superkingdom Metakaryota
 see Domain Eukaryota Chatton, 1925
      
 Kingdom Protozoa Goldfuss, 1818 - protozoa
        
 Subkingdom Dictyozoa Cavalier-Smith, 1991
          
 Branch Bikonta Cavalier-Smith, 1993
            
 Infrakingdom Neozoa Cavalier-Smith, 1993
              
 Parvkingdom Alveolata Cavalier-Smith, 1991
 see Superphylum Alveolata Cavalier-Smith, 1991
                
 Superphylum Heterokaryota Hickson, 1903 [monotypic]
                  
 Phylum Ciliophora Doflein, 1901 - ciliates
                    
 1 Class Spirotrichea Bütschli, 1889
                    
 2 Class Prostomatea Schewiakoff, 1896
                    
 3 Class Litostomatea Small & Lynn, 1981
                    
 4 Class Phyllopharyngea de Puytorac et al., 1974
                    
 5 Class Nassophorea Small & Lynn, 1981
                    
 6 Class Oligohymenophorea de Puytorac et al., 1974 - oligohymenophoreans
                    
 7 Class Colpodea Small & Lynn, 1981
                    
 8 Class Karyorelictea Corliss, 1974