S63
S63 may refer to:

 S-63 (encryption standard), an International Hydrographic Organization standard for encrypting and securing electronic navigational chart data
 S63: In case of accident by inhalation: remove casualty to fresh air and keep at rest, a safety phrase in chemistry
 S63 (Long Island bus), USA
 S63 postcode for Barnsley, Rotherham, UK
 INS Sindhurakshak (S63), a 1997 Indian Navy Sindhughosh class submarine
 Mercedes-Benz S63 AMG
 BMW S63 engine, the BMW Motorsport version of the N63 V8 engine