CK, Ck, or ck may refer to:
Science and technology Conductive keratoplasty, a type of refractive surgery Creatine kinase, an enzyme Cytokinin, a plant hormone Cytokeratin (CK1 to CK20), keratin proteins Cyanogen chloride, an inorganic chemical
Computing .ck, the Internet country code top-level domain for the Cook Islands Collective Knowledge (software), a framework for collaborative and reproducible research
Organizations Calvin Klein (fashion house), a fashion company CH. Karnchang, a Thai contractor and construction firm Chowking, a Filipino fast food chain Colombo Kings, a team participating in Lanka Premier League CK Hutchison Holdings, a multinational conglomerate headquartered in Hong Kong Bloods, a US-based street gang, from the nickname "Crip Killer" Circle K, an international chain of convenience stores
Transportation China Cargo Airlines (IATA code CK) Composite Corridor, a designation of British Rail carriages Chevrolet C/K, a model of pickup truck
People Louis C.K. (born 1967), American comedian Con Kolivas, Australian anaesthetist
Other uses ck (digraph), a letter combination used in spelling C-K theory (concept-knowledge theory), in design CK (album), a 1988 album by Chaka Khan Civilinis kodeksas, the Code of Lithuania Cranbrook Kingswood, a school in the US
See also CAK (disambiguation) KC (disambiguation)