The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Cathcart (star) (1 member)
- Cathcart System (1 member)
- Cathcart system (8 members)
- Caudillo Helmet Burnt Orange images (1 member)
- Caudillo Helmet Cobalt images (1 member)
- Caudillo Helmet Ghost White images (1 member)
- Caudillo Helmet Hazard images (1 member)
- Caudillo Helmet Steel images (1 member)
- Caudillo Helmet Wildfire images (1 member)
- Caudillo Helmet images (5 members)
- Cave (2 members)
- Caves (7 members)
- Caves and caverns (2 members)
- Cellin (16 members)
- Cellin images (36 members)
- Centauri IV images (1 member)
- Centauri I images (1 member)
- Centauri V images (1 member)
- Centauri system (11 members)
- Centralists (18 members)
- Centuries (23 members)
- Centurion images (33 members)
- Ceremonial Knife images (3 members)
- Cestulus (1 member)
- Character images (107 members)
- Characters (377 members)
- Charger images (1 member)
- Charon 2a images (1 member)
- Charon 2b images (1 member)
- Charon III images (1 member)
- Charon II images (1 member)
- Charon IV images (1 member)
- Charon I images (1 member)
- Charon System (0 members)
- Charon V images (1 member)
- Charon system (14 members)
- Checkmate Station (1 member)
- Checkmate Station images (3 members)
- Chemline Solutions (1 member)
- Chimera Communications (6 members)
- Chronicles (8 members)
- Chronos System (4 members)
- Chronos system (7 members)
- Chthonian Planet (7 members)
- Citadel images (8 members)
- Citation (1 member)
- Citation templates (17 members)
- Cities (44 members)
- CitizenCon (1 member)
- CitizenCon 2018 (9 members)