The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Broken links (11 members)
- Broken redirects (0 members)
- California (2 members)
- Cartouche links (0 members)
- Categories needing attention (7 members)
- Category management templates (3 members)
- Category namespace templates (1 member)
- Character-substitution templates (10 members)
- Check for country specific content (0 members)
- Cleanup templates (1 member)
- Client applications (10 members)
- Collapse templates (0 members)
- Colorado (1 member)
- CommonState (1 member)
- Communication templates (1 member)
- Community Administration (16 members)
- Community administration (0 members)
- Computer keys (2 members)
- Connecticut (7 members)
- Construction (133 members)