S
- Saar (1920–1959)
- St. Christopher (1870–1890)
- St. Helena (1856–)
- Saint Kitts (1980–)
- Saint Kitts and Nevis (1903–1980)
- Saint Lucia (1860–)
- Saint-Pierre and Miquelon (1885–)
- St. Thomas and Prince Islands (1869–)
- Saint Vincent and the Grenadines (1861–)
- St. Vincent Bequia (1984–)
- St. Vincent Canouan (1997–)
- St. Vincent Mustique (1997–)
- St. Vincent Union Islands (1984–)
- El Salvador (1867–)
- Samoa (1877–)
- San Marino (1877–)
- São Tomé and Príncipe (1869–)
- Sarawak (1869–1963)
- Saseno (1923)
- Saudi Arabia (1916–)
- Senegal (1887–)
- Senegambia and Niger (1903)
- Serbia (1866–1920)
- Serbia and Montenegro (2003–)
- Seychelles (1890–)
- Seychelles, Zil Elwannyen Sesel (1980–)
- Shanghai (1865–1896)
- Sharjah (1963–1968)
- Siberia (1919–1922)
- Sierra Leone (1859–)
- Singapore (1948–)
- Slovakia (1939–1945, 1993–)
- Slovenia (1991–)
- Solomon Islands (1907–)
- Somalia (1903–)
- Somali Coast (1894–1967)
- Somaliland
- Somaliland Protectorate (1903–1960)
- South Africa (1910–)
- Bophuthatswana (1977–1978)
- Ciskei (1981–1983)
- Transkei (1976–1989)
- Venda (1979–1982)
- South Arabia (1963–1966)
- South Australia (1855–1912)
- Southern Nigeria (1901–1912)
- Southern Rhodesia (1924–1964)
- South Georgia (1963–1992)
- South Ossetia (1994–)
- South Russia (1918–1919)
- South West Africa (1923–1990)
- Sovereign Military Order of Malta (1966–)
- Spain (1850–)
- Spanish Guinea (1902–1959)
- Spanish Morocco (1903–1955)
- Spanish Sahara (1924–1975)
- Spanish West Africa (1949–1951)
- Sri Lanka (1972–)
- Straits Settlements (1867–1945)
- Sudan (1897–)
- Suriname (1873–)
- Swaziland (1889–)
- Sweden (1855–)
- Switzerland (1850–)
- Syria (1919–)
Read more about this topic: List Of People On Stamps