C. marginatus

C. marginatus may refer to:
 * Callinectes marginatus, the or
 * Charadrius marginatus, the white-fronted plover or white-fronted sandplover
 * Chauliognathus marginatus, the margined soldier beetle
 * Cladodus marginatus, a prehistoric fish species
 * Coreus marginatus, the dock bug
 * Cryptanthus marginatus, a plant species endemic to Brazil