S100 or S-100 may refer to:

• S-100 bus, an early computer bus
• S-100, an International Hydrographic Organization standard
• S100 protein, low-molecular-weight proteins in vertebrates
• The road number used in the Netherlands for inner-city ring roads
• AVE Class 100, or S100, a high speed train
• Canon PowerShot S100, a camera
• Colyaer Freedom S100, a Spanish amphibious ultralight aircraft
• Colyaer Gannet S100, a Spanish ultralight flying boat
• Colyaer Martin3 S100 is a Spanish ultralight aircraft
• A class of WWII German E-Boat.
• Guild S-100, an electric guitar
• Lenovo IdeaPad S100, a netbook computer
• Qtek S100, a mobile phone
• Schiebel Camcopter S-100, an unmanned aerial vehicle
• Škoda 100, a 1970s car
• USATC S100 Class, a 1942 steam locomotive class

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