C31

C31 or C-31 may refer to:

Vehicles

 * Fokker C-31A Troopship, a Dutch military transport
 * HMS C31, a C-class submarine of the Royal Navy
 * Nissan Laurel C31, a Japanese sedan
 * Sauber C31, a Swiss Formula One car

Other uses

 * Blackstripe corydoras, a tropical freshwater fish
 * C-31 highway (Spain), in Catalonia
 * C31 road (Namibia)
 * Bill C-31, various legislation of the Parliament of Canada
 * Caldwell 31, an emission/reflection nebula
 * Channel 31 (disambiguation)
 * King's Gambit, Falkbeer Countergambit, a chess opening
 * C31, a London Cycleway