S55

S55 may refer to:

Aircraft

 * Savoia-Marchetti S.55, an Italian flying boat
 * Sikorsky S-55, an American helicopter
 * Sukhoi S-55, a proposed Russian fighter aircraft

Automobiles

 * BMW S55, an automobile engine
 * Mercedes-Benz S 55 AMG, a luxury car
 * Mercury S-55, an American full-size car
 * Shorland S55, a British armoured personnel carrier

Rail and transit

 * S55 (New York City bus) serving Staten Island
 * S55 (St. Gallen S-Bahn), a former S-Bahn line in Thurgau, Switzerland
 * S55 (ZVV), a former line of the Zürich S-Bahn
 * FGC line S55, a suburban train line in Catalonia, Spain

Other uses

 * S55 (star) in the constellation Sagittarius
 * Ariel 1, a British satellite
 * County Route S55 (Bergen County, New Jersey)
 * Explorer S-55 (satellite), a failed American spacecraft
 * INS Sindhughosh (S55), a submarine of the Indian Navy
 * Siemens S55, a mobile phone
 * Wandandian language