| Country | Independence |
| Somalia | 1 July 1960 (from a merger of British Somaliland that became independent from the UK on 26 June 1960 and Italian Somaliland that became independent from the Italian-administered UN trusteeship on 1 July 1960 to form the Somali Republic) |
| South Africa | 31 May 1910 (Union of South Africa formed from four British colonies: Cape Colony, Natal, Transvaal, and Orange Free State); 31 May 1961 (republic declared); 27 April 1994 (majority rule) |
| South Georgia and the South Sandwich Islands | void |
| South Sudan | 9 July 2011 (from Sudan) |
| Southern Ocean | void |
| Spain | 1492; the Iberian peninsula was characterized by a variety of independent kingdoms prior to the Muslim occupation that began in the early 8th century A.D. and lasted nearly seven centuries; the small Christian redoubts of the north began the reconquest almost immediately, culminating in the seizure of Granada in 1492; this event completed the unification of several kingdoms and is traditionally considered the forging of present-day Spain |
| Spratly Islands | void |
| Sri Lanka | 4 February 1948 (from the UK) |
| Sudan | 1 January 1956 (from Egypt and the UK) |
| Suriname | 25 November 1975 (from the Netherlands) |
| Svalbard | none (territory of Norway) |
| Swaziland | 6 September 1968 (from the UK) |
| Sweden | 6 June 1523 (Gustav VASA elected king) |
| Switzerland | 1 August 1291 (founding of the Swiss Confederation) |
| Syria | 17 April 1946 (from League of Nations mandate under French administration) |
| Taiwan | void |
| Tajikistan | 9 September 1991 (from the Soviet Union) |