77 selected
- S.C.A.D.T.A
- Saar (1920-1935)
- Saarland
- Saint Christopher-Nevis-Anguilla
- Saint Helena
- Saint Kitts
- Saint Lucia
- Saint Martin
- Saint Vincent and the Grenadines
- Saint-Pierre and Miquelon
- Sainte-Marie de Madagascar
- Samoa
- Samos
- San Marino
- Sao Tome and Principe
- Saudi Arabia
- Saxony
- Schleswig-Holstein
- Sealand - Cinderella
- Senegal
- Senegambia and Niger
- Serbia
- Serbia - Occupation of Banat-Backa
- Serbia - Occupation of Baranya
- Serbia - Occupation of Temesvar
- Serbia and Montenegro
- Seychelles
- Seychelles - Zil Eloigne Sesel
- Shanghai
- Sharjah
- Siam (Thailand)
- Siam - British Post Office [Bangkok]
- Sierra Leone
- Singapore
- Sleswick
- Slovakia
- Slovenia
- Solomon Islands
- Somali Coast - French Protectorate (Côte Française des Somalis)
- Somalia
- Somalia - Illegal Stamps
- Somalia - Puntland - Illegal Stamps
- Somaliland - British Protectorate
- South Africa
- South Australia
- South Georgia and the South Sandwich Islands
- South Kasai
- South Korea
- South Maluku - Cinderella (Maluku Selatan)
- South Sudan
- South Yemen [1967-1990] (People's Democratic Republic of Yemen - PDR)
- South-West Africa
- Southern Nigeria
- Southern Rhodesia
- Sovereign Military Order of Malta
- Soviet Union
- Spain
- Spain - Cinderella
- Spain - Local issues
- Spanish Guinea
- Spanish Sahara
- Spanish West Africa
- Spanish West Indies
- Sri Lanka (Ceylon)
- Stellaland
- Straits Settlements
- Sudan
- Suez Canal
- Suriname
- Swaziland (Eswatini)
- Sweden
- Sweden - Isö - Cinderella
- Sweden - Jul stamps
- Switzerland
- Switzerland - Cinderella
- Switzerland - Swiss Post abroad
- Syria
- Not filled in