S56

S56 may refer to:

Aircraft

 * Blériot-SPAD S.56, a family of prototype French airliners
 * Savoia-Marchetti S.56, an Italian flying boat
 * Sikorsky S-56, an American helicopter
 * Sukhoi S-56, a proposed Russian carrier fighter

Other uses

 * S56 (Long Island bus)
 * S56 (New York City bus) serving Staten Island
 * County Route S56 (Bergen County, New Jersey)
 * Explorer S-56 (satellite), a failed American spacecraft
 * GER Class S56, a British steam locomotive
 * INS Sindhudhvaj (S56), a submarine of the Indian Navy
 * Prince Skyline (S56), a Japanese automobile
 * S56: Dispose of this material and its container at hazardous or special waste collection point, a safety phrase
 * SOVIET SUBMARINE S-56
 * Siemens S56, a Siemens mobile phone