The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Grand Lane (1 member)
- GraphViz (1 member)
- Graphics (3 members)
- Gratis (1 member)
- Gravatars (1 member)
- Greens (1 member)
- Greg Maxwell (1 member)
- Grinders (1 member)
- Guerilla preservation (2 members)
- H. Margaret Wilson (1 member)
- HTML (2 members)
- HTTP (1 member)
- Hacking (2 members)
- Hamilton Hill (3 members)
- Hamilton Road (1 member)
- Hand planes (1 member)
- Hand tools (1 member)
- Handtools (1 member)
- HaveAnAdventure (1 member)
- Hcard (1 member)
- Heritage (4 members)
- Heritage interpretation (1 member)
- Hierarchies (1 member)
- Hiking (1 member)
- Hilton (1 member)
- Hipocracy (1 member)
- History (5 members)
- History of West Australia (1 member)
- Honesty (1 member)
- Hosting (2 members)
- Housemates (1 member)
- Houses (2 members)
- How I write (5 members)
- How Proust Can Change Your Life (1 member)
- Hush (1 member)
- Hyperlinks (1 member)
- Hypertext (1 member)
- I'm Sorry I Haven't A Clue (1 member)
- I.T. (1 member)
- IA Upload (1 member)
- IBM (5 members)
- ICT (1 member)
- ISAD(G) (1 member)
- ISOC (1 member)
- Identity (1 member)
- Image-flicker-plugin (0 members)
- Image Flicker plugin (3 members)
- Images (2 members)
- Imagination (1 member)
- Importing (2 members)