Encyclopedias, Almanacs, Transcripts, and Maps
- Citizens Against UFO Secrecy (CAUS)
- Citric Trees
- Citrus Trees
- Civets
- Civets
- Civets, Genets, and Linsangs: Viverridae
- Civil Court, Forensic Evidence
- CKM Matrix
- Claflin Sisters, Victoria (1838-1927) and Tennessee Celeste (1846-1923)
- Clairaudience
- Clam Worms, Sand Worms, and Tubeworms: Polychaeta
- Clan Morna
- Clancarty, Earl of (1911-)
- Clara (Clarissa Harlowe) Barton
- Claregate College
- Clarence Erwin McClung
- Clarence Norman Fenner
- Clarence Walton Lillehei
- Clarie, Thomas Cashin (1943-)
- Clark, Walter Houston (1902-1994)