SS or ss or Ss may be:

• Collar of SS in British heraldry, is an ornamental collar of many chained letters S; the "S" is said to stand for "[I serve my] sovereign"
• Corsair airline company IATA code
• Saints, often abbreviated e.g. "SS Peter and Paul"
• Sand Springs Railway
• Sassari province of Italy
• Schutzstaffel, a Nazi paramilitary force
• Shortstop, abbreviated SS, an infield defensive position in baseball
• Sláturfélag Suðurlands , the Icelandic company (Southern Association of Slaughter), commonly abbrivated as SS.
• Social security
• Social Studies
• Special Service soldiers in British service during World War II, later renamed Commandos.
• Special Science CPU, a rare implant in the MMORPG Neocron
• Stainless steel, common abbreviation for this metal alloy
• State Railway Exploitation Company, formerly the Dutch railway concern, see also Railway stations in the Netherlands#D
• Steamship (SS) (ship prefix)
• Stockholm Skins , a neo-nazi organization in Stockholm, Sweden
• Stockholms spårvägar , now a part of Storstockholms lokaltrafik
• Submarine not powered by nuclear energy (SS) (United States Navy designator), see SSN
• Super Sport (SS) is the abbreviation for the performance package that the Chevrolet automobile division of General Motors uses on certain models. It can include high-perfomance engine, suspension, tire and alternate body styling options. It was first used on the Impala model in 1961.
• Surface-to-surface missile of Soviet/Russian type, as listed by NATO reporting name (list of missiles)
• Swallow Sidecar, now Jaguar

• The ß ligature (German letter for double "s")
• United States Secret Service