The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Gallery pages about machines (1 member)
- GameCube (0 members)
- Gas technologies (0 members)
- Gases (1 member)
- Genera of Mammalia (1 member)
- Glaucidae (1 member)
- Glaucus (0 members)
- Granola (0 members)
- Helper templates (3 members)
- Hidden categories (15 members)
- Human activities (1 member)
- IOS games by name (1 member)
- Icon images that should use vector graphics (1 member)
- Icons by theme (1 member)
- Image generation subtemplates (3 members)
- Image icons (1 member)
- Image insertion templates (1 member)
- Image sets (2 members)
- Images by usage (1 member)
- Independent video game developers (1 member)
- Indie video games by name (2 members)
- Industrial technologies (1 member)
- Infobox templates: based on Information template (1 member)
- Information processing (1 member)
- Information science (1 member)
- Information systems (1 member)
- Internal link templates (2 members)
- Internationalised category header templates (1 member)
- Internationalization templates (3 members)
- Internet (1 member)
- Internet services (1 member)
- Interwiki link templates (2 members)
- Java platform game (1 member)
- Jolly Roger flags with skull and crossbones (1 member)
- Knowledge representation (1 member)
- Language link templates (2 members)
- Language templates (2 members)
- Layout templates (12 members)
- Letters in blue circles (1 member)
- License tags attribution (3 members)
- License tags full-text (2 members)
- License tags of the United States (1 member)
- License tags share-alike (3 members)
- Life sciences (1 member)
- Linux video games by name (1 member)
- Localisation templates (2 members)
- Location not applicable (1 member)
- Logos of video games by name (1 member)
- MacOS video games by name (1 member)
- Magnifying glass icons (0 members)