S-55

S55, S.55 or S-55 may refer to:
* S55 (New York City bus) serving Staten Island
* County Route S55, a county route in Bergen County, New Jersey
* INS Sindhughosh (S55), a Sindhughosh class submarines of the Indian Navy
* Sikorsky S-55, an American helicopter better known by its American military designation of H-19 Chickasaw
* Savoia-Marchetti S.55, an Italian flying boat aeroplane
* Siemens S55, a 2002 model of cellular telephone
* a Zürich S-Bahn line