The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Computer Systems (0 members)
- Computer science navigational boxes (1 member)
- Conceptions of self (0 members)
- Concepts in the philosophy of mind (1 member)
- Conformity (1 member)
- Control (social and political) (1 member)
- Crimson Horizon Sector (3 members)
- Cross Setting Characters (6 members)
- Cross Setting Non-Player Characters (1 member)
- Culture (1 member)
- Cybernetics (24 members)
- Danish writer navigational boxes (1 member)
- Dark triad (1 member)
- Darkian Churarius Sectors (1 member)
- Darkian Churarius Star Systems (2 members)
- Data templates (2 members)
- Decommissioned (1 member)
- Deletion Issues (4 members)
- Delphi (1 member)
- Delta Nadacan Sector (9 members)
- Denied Characters (0 members)
- Denied or Banned (3 members)
- Denied or Banned Characters (0 members)
- Destroyed Facilities (2 members)
- Disambiguation (28 members)
- Disambiguation message boxes (1 member)
- Documentation assistance templates (1 member)
- Documentation see also templates (1 member)
- Ego psychology (0 members)
- Eldritch Doll Non-Player Characters (4 members)
- Elemental Characters (2 members)
- Elemental Non-Player Characters (1 member)
- Embers of Soteria (45 members)
- Embers of Soteria Characters (54 members)
- Embers of Soteria Non-Player Characters (10 members)
- Epsilon Tatva Sector (7 members)
- Ethical schools and movements (1 member)
- Euthenics (1 member)
- Exclude in print (1 member)
- Familiars (1 member)
- Fauna (1 member)
- File message boxes (4 members)
- File namespace templates (2 members)
- Files with no machine-readable source (1 member)
- Footnote templates (1 member)
- French writer navigational boxes (1 member)
- HSD Sectors (0 members)
- HSD Space Sectors (1 member)
- HSD Star Systems (1 member)
- Hatnote modules (1 member)