C12 or C-12 may be: · C12, the cyclic group with 12 elements in group theory · Carbon-12, most abundant stable isotope of carbon · C-12 Huron, a logistics support aircraft of the U.S. Military · C-12 Vega, an early transport of the United States Army Air Corps · HMS C12, a British C class submarine of the Royal Navy · USS Columbia , a light cruiser of the United States Navy C12