C56

C56 or C-56 may refer to:
 * C-56 (Michigan county highway)
 * ARM Cadete Juan Escutia, an Admirable-class minesweeper of the Mexican Navy
 * Caldwell 56, a planetary nebula
 * Hexachlorocyclopentadiene, an organochlorine compound
 * JNR Class C56, a class of Japanese steam locomotive
 * Lockheed C-56 Lodestar, an American military aircraft
 * Ovarian cancer
 * Sickness Insurance (Sea) Convention, 1936 of the International Labour Organization
 * Two Knights Defense, a chess opening