The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Filetype icons (1 member)
- Flags with black fields (1 member)
- Fluid technology (1 member)
- Formatting templates (1 member)
- Free software (1 member)
- Free software by name (3 members)
- Fédération Cynologique Internationale dog breeds (1 member)
- GNOME (1 member)
- GNOME Desktop icons (1 member)
- GNOME Desktop icons, emblems (1 member)
- 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)
- Gallery pages about machines (1 member)
- GameCube (0 members)
- Gas technologies (0 members)
- Gases (1 member)
- Genera of Mammalia (1 member)
- Ghosts (0 members)
- 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)
- Immortality (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)