The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Audio (7 members)
- Authors (26 members)
- Autonomy (3 members)
- BSD (1 member)
- Bands (58 members)
- Bash (3 members)
- Biology (8 members)
- Bleeding Edge (2 members)
- Blinkenlights (29 members)
- Blinkensisters (7 members)
- Blog (1 member)
- Blogs (4 members)
- Body (1 member)
- Books (50 members)
- Bots (62 members)
- Boxes (45 members)
- Broken jargon pages (1 member)
- Buddhism (6 members)
- Buggy jargon pages (1 member)
- Bush (3 members)
- CC-BY-2.0 (2 members)
- CC-BY-NC-ND-2.0 (1 member)
- CC-BY-SA-2.0 (1 member)
- CC-BY-SA-2.5 (5 members)
- CC-by-sa-Bild (1 member)
- CCC (23 members)
- CIA (1 member)
- Cats (2 members)
- Censorship (4 members)
- Chemistry (1 member)
- Christian (4 members)
- Club Der U2-Liebhaber (1 member)
- Codes (43 members)
- Cologne (4 members)
- Comedy (4 members)
- Communications (4 members)
- Computer (452 members)
- Concord (15 members)
- Conspiracy (53 members)
- Conventions (3 members)
- Converter (11 members)
- Copyrighted free use (1 member)
- Corporations (14 members)
- Countries (1 member)
- Cowsay (54 members)
- Crypto (19 members)
- Cybernetics (1 member)
- Cyborg (1 member)
- DIY (7 members)
- Debian (30 members)