Encyclopedias, Almanacs, Transcripts, and Maps
- Simonsen, Roberto Cochrane (1889–1948)
- SIMPLE SENTENCE
- Simplicius (fl. c. 530)
- SIMPLIFIED SPELLING SOCIETY
- Simpson, Adele Smithline
- Simpson, Orenthal James ("O. J.")
- Simulation Theory
- Sinai Peninsula
- Sinarquismo
- Since 1825
- Since 1830
- Since 1889
- Since 1910
- Since 1945
- Since 1959
- Since 1990
- Since 1990
- Since 1990
- Since Independence
- Sinclair, Alfredo (1914–)