The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Companies based in Kyoto (1 member)
- Companies by name (1 member)
- Companies listed on NASDAQ (1 member)
- Companies listed on the Frankfurt Stock Exchange (1 member)
- Companies listed on the Tokyo Stock Exchange (1 member)
- Compiz (1 member)
- Computer hardware (1 member)
- Computing (1 member)
- Concepts (0 members)
- Concepts in metaphysics (2 members)
- Concepts in physics (1 member)
- Conceptual distinctions (1 member)
- Conceptual systems (1 member)
- Created with:I18nTemplates (1 member)
- Created with ... I18nTemplates (1 member)
- Created with Inkscape-undef (1 member)
- Cross-platform software (2 members)
- Cubes in pixel art (1 member)
- Cubic objects (1 member)
- Custom license tags (1 member)
- Deltarune (1 member)
- Deltarune logos (0 members)
- Deprecated templates (1 member)
- Desktop environments (1 member)
- Dimensions (1 member)
- Dog breeds by name (1 member)
- Domains (biology) (1 member)
- Electronics manufacturers of Japan (1 member)
- Energy technology (1 member)
- Entities (1 member)
- Eukaryota (0 members)
- Eutheria (1 member)
- Extant Miocene first appearances (1 member)
- Extant Neogene first appearances (1 member)
- Fifth-generation video game consoles (1 member)
- File emblems (1 member)
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- Flags with black fields (1 member)
- Fluid technology (1 member)
- Formatting templates (1 member)
- Free software (1 member)
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- Fédération Cynologique Internationale dog breeds (1 member)
- GNOME (1 member)
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- GPL license tags (1 member)
- Gallery pages about computer hardware (1 member)
- Gallery pages about computing (1 member)
- Gallery pages about information technology companies (1 member)