| Clare, Iowa | Clare, Michigan | Clare, New York |
| Claremont, Illinois | Claremont, Minnesota | Claremont, New Hampshire |
| Claremont, North Carolina | Claremont, South Dakota | Claremont, Virginia |
| Claremore, Oklahoma | Clarence (2014 TV series) | Clarence Acuña |
| Clarence Day | Clarence Goodson | Clarence King |
| Clarence L. Johnson | Clarence Nash | Clarence Seedorf |
| Clarence Township, Michigan | Clarence Williams III | Clarence, Iowa |
| Clarence, New York | Clarendon Hills, Illinois | Clarendon Township, Michigan |
| Clarendon, Arkansas | Clarendon, New York | Clarendon, Quebec |
| Clarendon, Texas | Clarendon, Vermont | Clarias batrachus |
| Clariden | Clariidae | CLARINASE |
| Clarinda, Iowa | Clarinet | Clarington, Ohio |
| Clarion County, Pennsylvania | Clarion, Iowa | Clarissa, Minnesota |
| Clarithromycin | Clark County, Indiana | Clark County, Wisconsin |
| Clark Duke | Clark Gable | Clark International Airport |
| Clark Johnson | Clark L. Hull | Clark Township, Michigan |
| Clark, South Dakota | Clarkdale, Arizona | Clarke Carlisle |
| Clarke County, Alabama | Clarke's three laws | Clarkedale, Arkansas |
| Clarkesville, Georgia | Clarkfield, Minnesota | Clarkia amoena |
| Clarks Grove, Minnesota | Clarks Hill, Indiana | Clarks, Nebraska |
| Clarksburg, Massachusetts | Clarksburg, Ohio | Clarksburg, Tennessee |
| Clarksburg, West Virginia | Clarksdale, Mississippi | Clarkson, Kentucky |
| Clarkson, New York | Clarkston, Georgia | Clarkston, Michigan |
| Clarkston, Utah | Clarkston, Washington | Clarkstown, New York |
| Clarksville City, Texas | Clarksville, Allegany County, New York | Clarksville, Arkansas |
| Clarksville, Indiana | Clarksville, Iowa | Clarksville, Michigan |
| Clarksville, New Hampshire | Clarksville, Ohio | Clarksville, Tennessee |
| Clarksville, Texas | Clarksville, Virginia | Clarkton, North Carolina |
| Clarno, Wisconsin | Clarques | Clash of Civilizations |
| Clash of Clans | Clash of clans | Clash of Loyalties |
| Clash of the Titans (2010 film) | Clasper | Class (biology) |
| Class (computer programming) | Class conflict | Class consciousness |
| Class discrimination | Class in Marxist theory | Class struggle |
| Classes of computers | Classful network | Classic car |
| Classic metal | Classical antiquity | Classical architecture |
| Classical compound | Classical conditioning | Classical electromagnetism |
| Classical electron radius | Classical element | Classical liberalism |
| Classical limit | Classical mechanics | Classical order |
| Classical physics | Classical planet | Classicism |
| Classics | Classification of finite simple groups | Classification of mental disorders |
| Classification society | Classified advertising | Classless Inter-Domain Routing |
| Classroom | Classroom design | Clathrate hydrate |
| Clatonia, Nebraska | Clatskanie, Oregon | Claude Adrien Helvétius |
| Claude Étienne Savary | Claude Bernard | Claude Berri |
| Claude Cahen | Claude Chevalley | Claude Cohen-Tannoudji |
| Claude Dornier | Claude Etienne Savary | Claude Faraggi |
| Claude Frollo | Claude Gaspard Bachet de Méziriac | Claude Giroux |
| Claude Henri de Rouvroy, comte de Saint-Simon | Claude Joseph Rouget de Lisle | Claude Lévi-Strauss |
| Claude Le Roy | Claude Louis Berthollet | Claude Makélélé |
| Claude Nicolas Ledoux | Claude Puel | Claude Reignier Conder |
| Claude Rich | Claude Saumaise | Claude Shannon |
| Claude Simon | Claude, Texas | Claude-Arnaud Rivenet |
| Claude-Étienne Savary | Claude-Etienne Savary | Claude-Louis Navier |
| Claudette Colbert | Claudette Colvin | Claudia Cardinale |
| Claudia Ciesla | Claudia Pechstein | Claudia Schiffer |
| Claudio Bellucci | Claudio Biaggio | Claudio Bravo (footballer) |
| Claudio Caniggia | Claudio García | Claudio Gentile |
| Claudio Husaín | Claudio López (footballer) | Claudio Marchisio |
| Claudio Morel Rodríguez | Claudio Pizarro | Claudio Puglisi |
| Claudio Ranieri | Claudio Reyna | Claudio Sánchez-Albornoz |
| Claudio Sánchez-Albornoz y Menduiña | Claudio Suárez | Claudio Terzi |
| Claudiu Bleonț | Claudius | Claudius Bombarnac |
| Claudius Gothicus | Claudius James Rich | Claudius Salmasius |
| Claus Bo Larsen | Claus Jensen | Claus von Stauffenberg |
| Clauseneae | Clauseninae | Clausius–Clapeyron relation |
| Claussenomyces atrovirens | Claustrum | Clavam |
| Claverack, New York | Claviceps | Claviceps africana |
| Claviceps annulata | Claviceps cinerea | Claviceps fusiformis |
| Claviceps glabra | Claviceps inconspicua | Claviceps litoralis |
| Claviceps lutea | Claviceps pallida | Claviceps setulosa |
| Claviceps sorghi | Claviceps sorghicola | Claviceps viridis |
| Claviceps zizaniae | Clavicipitaceae | Clavicle |
| Clavicle fracture | Clavigo (play) | Clavipectoral fascia |
| Clavulanic acid | Claw | Clawson, Michigan |
| Clawson, Utah | Claxton, Georgia | Clay |
| Clay Banks, Wisconsin | Clay Center, Kansas | Clay Center, Ohio |
| Clay City, Illinois | Clay City, Indiana | Clay City, Kentucky |
| Clay County, Alabama | Clay County, Florida | Clay County, Indiana |
| Clay County, Mississippi | Clay County, Tennessee | Clay Shirky |
| Clay Township, Michigan | Clay, Kentucky | Clay, New York |
| Clay, West Virginia | Clay–water interaction | Claybanks Township, Michigan |
| Claybrook sign | Claycomo, Missouri | Claymore (manga) |
| Claypool, Indiana | Clayton (town), Wisconsin | Clayton (village), New York |
| Clayton Township, Arenac County, Michigan | Clayton Township, Genesee County, Michigan | Clayton, Crawford County, Wisconsin |
| Clayton, Delaware | Clayton, Georgia | Clayton, Illinois |
| Clayton, Indiana | Clayton, Iowa | Clayton, Kansas |
| Clayton, Louisiana | Clayton, Michigan | Clayton, New Mexico |
| Clayton, New York | Clayton, North Carolina | Clayton, Ohio |
| Clayton, Oklahoma | Clayton, Winnebago County, Wisconsin | Clayville, New York |
| Cláudio Taffarel | Cléber Santana | Clémence Matutu |
| Clément Ader | Clément Chantôme | Clément Grenier |
| Clément Huart | Clément Marot | Cléty |
| Cléver Chalá | Cle Kooiman | Clea DuVall |
| Clean-in-place | Cleaner | Cleaning validation |
| Cleanroom | Cleanroom Software Engineering | Cleanth Brooks |
| Cleanthes | Cleanthony Early | Clear cell |
| Clear cell adenocarcinoma | Clear cell squamous cell carcinoma | Clear Creek, Wisconsin |
| Clear ice | Clear Lake Shores, Texas | Clear Lake, Illinois |
| Clear Lake, Indiana | Clear Lake, Iowa | Clear Lake, Minnesota |
| Clear Lake, South Dakota | Clear Lake, Wisconsin | Clear Spring, Maryland |
