- Cabbage Bug
- Cackling Goose
- Cactus Wren
- Calico Pennant
- California Bumble Bee
- California Gall Wasp
- California Ground Squirrel
- California Gull
- California King Snake
- California Mussel
- California Newt
- California Quail
- California Scrub-Jay
- California Sea Lion
- California Seahare
- California Sister
- California Slender Salamander
- California Thrasher
- California Tortoiseshell
- California Towhee
- Camptopus lateralis
- Canada Goose
- Canada Jay
- Canada Warbler
- Canadian Tiger Swallowtail
- Cane Toad
- Canestrini's Harvestman
- Cannonball Jelly
- Cantharis livida
- Canvasback
- Canyon Towhee
- Canyon Tree Frog
- Canyon Wren
- Cape May Warbler
- Cape Weaver
- Caper White
- Capricorn beetle
- Capybara
- Cardinal Butterfly
- Cardinal Meadowhawk
- Caribbean Bluehead Wrasse
- Caribbean Land Hermit Crab
- Carolina Chickadee
- Carolina Grasshopper
- Carolina Mantis
- Carolina Saddlebags
- Carolina Satyr
- Carolina Sphinx
- Carolina Wren
- Carpenterworm Moth
- Carrhotus xanthogramma
- Carrion Crow
- Carrot Seed Moth
- Caspian Gull
- Caspian Tern
- Cassin's Kingbird
- Cassius Blue
- Catalpa Sphinx
- Cattle Tyrant
- Cecropia Moth
- Cedar Waxwing
- Celery Leaftier Moth
- Central American Agouti
- Central American White-faced Capuchin
- Central Ratsnake
- Ceraunus Blue
- Chalk-browed Mockingbird
- Chalk-fronted Corporal
- Chalkhill Blue
- Chalky Percher
- Channel Catfish
- Checkered White
- Chequered Skipper
- Cherry Gall Wasp
- Chestnut Carpenter Ant
- Chestnut Heath
- Chestnut Teal
- Chestnut-backed Chickadee
- Chestnut-sided Warbler
- Chicatana Leafcutter Ant
- Chickweed Geometer Moth
- Chimango Caracara
- Chimney Swift
- Chinese Blackbird
- Chinese Mantis
- Chinese Pond-Heron
- Chinese Yellow Swallowtail
- Chipping Sparrow
- Chocolate Pansy
- Chocolate-band Snail
- Christmas Jewel Spider
- Chrysopa oculata
- Chukar
- Cinnabar moth
- Cinnamon Hummingbird
- Cinnamon Teal
- Cinnamon-rumped Seedeater
- Cirl Bunting
- Citrine Forktail
- Citrine Wagtail
- Citrus Flatid Planthopper
- Clark's Grebe
- Clark's Nutcracker
- Clay-colored Sparrow
- Clay-colored Thrush
- Clemens' Grass Tubeworm Moth
- Cleopatra Butterfly
- Cliff Swallow
- Cloaked Marvel
- Cloaked Minor
- Clouded Border
- Clouded Buff
- Clouded Drab
- Clouded Skipper
- Clouded Sulphur
- Clouded Yellow
- Cloudless Sulphur
- Clover Hayworm Moth
- Clymene Moth
- Coal Tit
- Cocoi Heron
- Codling Moth
- Collared Aracari
- Collared Kingfisher
- Collared Peccary
- Colorado Potato Beetle
- Columbian Ground Squirrel
- Common Aerial Yellowjacket
- Common Assassin Bug
- Common Atlantic Slippersnail
- Common Bagworm Moth
- Common Basilisk
- Common Black Hawk
- Common Blue
- Common Blue Damselfly
- Common Blue Mud-dauber Wasp
- Common Bluebottle
- Common Bluetail
- Common Bluetongue
- Common Bottlenose Dolphin
- Common Brimstone
- Common Bronzewing
- Common Brown
- Common Brushtail Possum
- Common Buckeye
- Common Bulbul
- Common Buzzard
- Common candy-striped spider
- Common Carder Bumble Bee
- Common Cardinal Beetle
- Common Carpet Moth
- Common Cerulean
- Common Chaffinch
- Common Checkered-Skipper
- Common Chiffchaff
- Common Chuckwalla
- Common Coachwhip
- Common Cockchafer
- Common Coot
- Common Crane
- Common Crimson-and-gold Moth
- Common Crow
- Common Cuckoo
- Common Darter
- Common Dolphin
- Common Drone Fly
- Common Dwarf Gecko
- Common Eastern Bumble Bee
- Common Eastern Firefly
- Common Eastern Velvet Ant
- Common Eider
- Common European Ambersnail
- Common European Greenbottle Fly
- Common European Scorpionfly
- Common European Yellowjacket
- Common Evening Brown
- Common Field Grasshopper
- Common Firecrest
- Common Five-lined Skink
- Common Flatwing
- Common Flower Fly
- Common Footman
- Common Froghopper
- Common Gallinule
- Common Garter Snake
- Common Globetail
- Common Gluphisia Moth
- Common Golden-mantled Ground Squirrel
- Common Goldeneye
- Common Grackle
- Common Grass Yellow
- Common Grass-veneer
- Common Green Darner
- Common Green Grasshopper
- Common Green June Beetle
- Common Greenshank
- Common Ground Dove
- Common Gull
- Common Heath
- Common Hedgehog
- Common Hoopoe
- Common House Spider
- Common Idia Moth
- Common Jay
- Common Kingfisher
- Common Lagoon Fly
- Common Leaf Weevil
- Common Leopard
- Common Loon
- Common Looper Moth
- Common Lovebug
- Common Maquis Grasshopper
- Common Marble
- Common Merganser
- Common Mestra
- Common Mormon Swallowtail
- Common Murre
- Common Myna
- Common Nettle-tap
- Common Nighthawk
- Common Oak Moth
- Common Octopus
- Common Palmfly
- Common Parasol
- Common Periwinkle
- Common Picture Wing
- Common Picture-winged Fly
- Common Pierrot
- Common Pill Woodlouse
- Common Pochard
- Common Quaker
- Common Raccoon
- Common Raven
- Common Red Soldier Beetle
- Common Redshank
- Common Redstart
- Common Reed Warbler
- Common Ringed Plover
- Common Ringlet
- Common Rose Swallowtail
- Common Rosefinch
- Common Rough Woodlouse
- Common Sagebrush Lizard
- Common Sailer
- Common Sandpiper
- Common Shelduck
- Common Shiny Woodlouse
- Common Side-blotched Lizard
- Common Slowworm
- Common Snapping Turtle
- Common Snipe
- Common Sootywing
- Common Spangle Gall Wasp
- Common Spitting Spider
- Common Spotted Whiptail
- Common Spreadwing
- Common Squirrel-Cuckoo
- Common Striped Woodlouse
- Common Sun Skink
- Common Swift
- Common Swift Moth
- Common Tachinid
- Common Tailorbird
- Common Tan Wave
- Common Tern
- Common Tiger Butterfly
- Common Tody-Flycatcher
- Common True Katydid
- Common Two-banded Seabream
- Common Wall Lizard
- Common Watersnake
- Common Waxbill
- Common Whelk
- Common Whitetail
- Common Winter Damselfly
- Common Wood-Nymph
- Common Wood-Pigeon
- Common Yellow Conch
- Common Yellowthroat
- Condylostylus patibulatus
- Confused Eusarca Moth
- Convergent Lady Beetle
- Convolvulus Hawkmoth
- Cooper's Hawk
- Cope's Gray Tree Frog
- Copper Chafer
- Copper Demoiselle
- Coppersmith Barbet
- Coppery Leafhopper
- Copse Snail
- Corn Bunting
- Corn Earworm Moth
- Coronet
- Costa's Hummingbird
- Cotton Bollworm Moth
- Coyote
- Coypu
- Cream-spot Tiger
- Cream-spotted Ladybird
- Creamy-bellied Thrush
- Creek Chub
- Crested Anole
- Crested Caracara
- Crested Lark
- Crested Myna
- Crested Pigeon
- Crested Serpent-Eagle
- Crested Tit
- Cricket-bat Orbweaver
- Crimson Marsh Glider
- Crimson Rosella
- Crimson-speckled Flunkey
- Crimson-tailed Marsh Hawk
- Cross Orbweaver
- Cuban Tree Frog
- Curlew Sandpiper
- Curve-billed Thrasher
- Curved-toothed Geometer Moth