S45 may refer to:
Aviation Blériot-SPAD S.45, a French biplane airliner SABCA S-45bis, a Belgian bomber Short S.45, a British biplane trainer Short S.45 Seaford, a British flying boat Sikorsky S-45, a proposed American flying boat Siletz Bay State Airport, in Lincoln County, Oregon, United States
Rail and transit S45 (Berlin), an S-Bahn line in Germany S45 (Long Island bus), United States S45 (Vienna), an S-Bahn line in Austria
Other uses Canon PowerShot S45, a digital camera Explorer S-45 (satellite), a failed American spacecraft S45: In case of accident or if you feel unwell seek medical advice immediately (show the label where possible), a safety phrase , a submarine of the Indian Navy Siemens S45, a mobile phone Sulfur-45, an isotope of sulfur , a submarine of the United States Navy S45, a postcode district in Chesterfield, England Saviem S45, a Savien bus model
See also 45S (disambiguation)