| Callistophytopsida | see Pteridospermophyta |
| Carpediemonada | EUKARYA>EXCAVATA>EUEXCAVATA>CARPEDIEMONADA |
| Catoniopsida | see Pteridospermophyta |
| Centrohelomonada | EUKARYA>CHROMALVEOLATA>HACROBIAE>CENTROHELOMONADA |
| Cephalochordata | EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>BILATERIA>DEUTEROSTOMATA>CEPHALOCHORDATA |
| Ceratophyllidopsida | EUKARYA>ARCHAEPLASTIDA>VIRIDIPLANTAE>STREPTOBIONTA>EMBRYOPHYTA>TRACHEOPHYTA>SPERMOPHYTA>ANGIOSPERMOPHYTA>CERATOPHYLLIDOPSIDA |
| Cercozoa | EUKARYA>CHROMALVEOLATA>RHIZARIAE>CERCOZOA |
| Chaetognatha | EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>BILATERIA>PROTOSTOMATA>CHAETOGNATHA |
| Charophyceae | see Charophyta |
| Charophyta | EUKARYA>ARCHAEPLASTIDA>VIRIDIPLANTAE>STREPTOBIONTA>CHAROPHYTA |
| Cheliceriformes | EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>BILATERIA>PROTOSTOMATA>ECDYSOZOA>PANARTHROPODA>ARTHROPODA>CHELICERIFORMES |
| Chlorobacteria | EUBACTERIA>PROTEOBACTERIAE>CHLOROSULFATAE>CHLOROBACTERIA |
| Chlorobionta | see Green Algae |
| Chloroflexae | EUBACTERIA>PROTEOBACTERIAE>CHLOROFLEXAE |
| Chloroflexobacteria | EUBACTERIA>PROTEOBACTERIAE>CHLOROFLEXAE>CHLOROFLEXOBACTERIA |
| Chlorokybophyceae | see Charophyta |
| Chlorophyceae | see Chlorophyta |
| Chlorophyta | EUKARYA>ARCHAEPLASTIDA>VIRIDIPLANTAE>CHLOROBIONTA>CHLOROPHYTA |
| Chlorosulfatae | EUBACTERIA>PROTEOBACTERIAE>CHLOROSULFATAE |
| Choanoflagellata | EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>CHOANOZOA>CHOANOFLAGELLATA |
| Choanozoa | see Animalia |
| Chondrichthyes | EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>BILATERIA>DEUTEROSTOMATA>VERTEBRATA>GNATHOSTOMATA>CHONDRICHTHYES |
| Chordata | see Deuterostomata |
| Chromalveolata | EUKARYA>CHROMALVEOLATA |
| Chromophytes | see Heterokontae |
| Chrysophyta | EUKARYA>CHROMALVEOLATA>HETEROKONTAE>CHRYSOPHYTA |
| Chytridiomycetes | see Chytridiomycota |
| Chytridiomycota | EUKARYA>OPISTHOKONTA>UNIKONTA>FUNGI>BASAL FUNGI>CHYTRIDIOMYCOTA |
| Ciliophora | EUKARYA>CHROMALVEOLATA>ALVEOLATAE>CILIOPHORA |
| Cladoxylidopsida | see Pteridophyta |
| Cnidaria | EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>DIPLOBLASTEA>CNIDARIA |
| Coenopteridopsida | see Pteridophyta |
| Coleochaetophyceae | see Charophyta |
| Coniferophyta | EUKARYA>ARCHAEPLASTIDA>VIRIDIPLANTAE>STREPTOBIONTA>EMBRYOPHYTA>TRACHEOPHYTA>SPERMOPHYTA>CONIFEROPHYTA |
| Conodontomorphi | EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>BILATERIA>DEUTEROSTOMATA>VERTEBRATA>CONODONTOMORPHI |
| Conosa | EUKARYA>UNIKONTA>AMOEBOZOA>AMOEBOZOAE>CONOSA |
| Cordaitopsida | see Coniferophyta |
| Craniata | see Vertebrata |
| Crenarchaea | ARCHAEA>CRENARCHAEA |
| Crenarchaeota | ARCHAEA>CRENARCHAEA>CRENARCHAEOTA |
| Crustacea | EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>BILATERIA>PROTOSTOMATA>ECDYSOZOA>PANARTHROPODA>ARTHROPODA>CRUSTACEA |
| Cryptomonada | EUKARYA>CHROMALVEOLATA>HACROBIAE>CRYPTOMONADA |
| Ctenophora | EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>DIPLOBLASTEA>CTENOPHORA |
| Cupressopsida | see Coniferophyta |
| Cyanidiophyta | EUKARYA>ARCHAEPLASTIDA>RHODOPLANTAE>CYANIDIOPHYTA |
| Cyanobacteria | EUBACTERIA>OXYPHOTOBACTERIA>CYANOBACTERIA |
| Cycadeoiodophyta | EUKARYA>ARCHAEPLASTIDA>VIRIDIPLANTAE>STREPTOBIONTA>EMBRYOPHYTA>TRACHEOPHYTA>SPERMOPHYTA>CYCADEOIDOPHYTA |
| Cycadophyta | EUKARYA>ARCHAEPLASTIDA>VIRIDIPLANTAE>STREPTOBIONTA>EMBRYOPHYTA>TRACHEOPHYTA>SPERMOPHYTA>CYCADOPHYTA |
| Cycliophora | EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>BILATERIA>PROTOSTOMATA>SPIRALIA>TROCHOZOA>POLYZOA>CYCLIOPHORA |
| Cyclostomata | see Vertebrata |
