C. marginatus may refer to:Callinectes marginatus, the sharptooth swimcrab or marbled swimcrab 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