Saint-Pierre and Miquelon
San Ġwann
San Diego
Santander
Scotland - Royal Banner
Senegal
Serbian Orthodox Church
Seychelles
Sicily
Sikkim (1877-c.1914)
Slovenia - Army Flag
Sochi
Solomon Islands - Civil Ensign
Solomon Islands - Naval Ensign
South Africa
South Africa - Naval Ensign
South Sudan
South Vietnam (1949-1975)
Soviet Union (1923-1991)
Spain
Spain - Civil Flag and Ensign
Sri Lanka
Sri Lanka - Naval Ensign
St. Eustatius