C12

C12, C.XII or C-12 may be:
 * LNER Class C12, a class of British 4-4-2T locomotives
 * C12 Workmen's Compensation (Agriculture) Convention, 1921
 * C-12 Huron, a logistics support aircraft of the U.S. Military (military versions of the Beechcraft Super King Air)
 * C-12 Vega, an early transport of the United States Army Air Corps
 * Albatros C.XII, a World War I German military reconnaissance aircraft
 * Autovia C-12, a highway in Catalonia, Spain
 * Cierva C.12, a 1927 British experimental autogyro
 * HMS C12, a British C-class submarine of the Royal Navy
 * JNR Class C12, a class of Japanese steam locomotive
 * Sauber C12, a 1993 racing car
 * Spyker C12 Zagato, a 2007 Dutch car
 * USS Columbia (C-12), a light cruiser of the United States Navy
 * C-12: Final Resistance, a video game for PlayStation
 * Caldwell 12 (NGC 6945, the Fireworks Galaxy), an intermediate spiral galaxy in the constellations Cepheus and Cygnus
 * The 12th century
 * Carbon-12, the most abundant stable isotope of carbon
 * Malignant neoplasm of piriform sinus ICD-10 code
 * Bill C-12 in Canadian law