75 selected
- Cambodia (Khmer Republic)
- Cameroon
- Canada
- Cape Juby
- Cape of Good Hope
- Cape Verde
- Caribbean Netherlands
- Carinthia
- Carpatho-Ukraine
- Cavalle (Greece - Cavala [French postoffice])
- Cayman Islands
- Central African Republic / Empire
- Central African Republic / Empire - Illegal Stamps
- Central Lituania
- Ceylon (Sri Lanka)
- Chad
- Chad - Illegal Stamps
- Chile
- Chili - Occupation of Peru
- China - British post offices
- China - Central China
- China - East China
- China - French post offices
- China - German post offices
- China - Italian post offices
- China - Japanese post offices
- China - North China - Occupation by Japan
- China - Northeast China
- China - Northern China
- China - Northwest China
- China - People's Republic
- China - Russian post offices
- China - Shanghai and Nanjing - Occupation by Japan
- China - South China
- China - Southwest China
- China [1878-1949]
- Christmas Island
- Cilicia (France [1919-1921] - Occupation of Turkey - Cilicia)
- Ciskei
- Cocos (Keeling) Islands
- Colombia
- Colombia - Antioquia
- Colombia - Bogota
- Colombia - Bolivar
- Colombia - Boyaca
- Colombia - Cucuta
- Colombia - Cundinamarca
- Colombia - Medellin
- Colombia - Santander
- Colombia - Tolima
- Comoros
- Comoros - Illegal Stamps
- Congo-Brazzaville
- Congo-Brazzaville - Illegal Stamps
- Congo-Kinshasa (Zaïre)
- Congo-Kinshasa - Illegal Stamps
- Cook Islands
- Costa Rica
- Côte Française des Somalis (Somali Coast - French Protectorate)
- Crete
- Crete - Austrian post offices
- Crete - French post offices
- Crete - Italian post office [Chania]
- Croatia
- Croatia - Cinderella
- Croatia [1991-1997] - Republic of Serbian Krajina
- Cuba
- Cuba - Spanish colony
- Curaçao
- Cyprus
- Cyrenaica
- Czechia
- Czechoslovakia
- Czechoslovakia - Local revolution issues
- Czechoslovakia - Voting area East-Silesia
- Not filled in