The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- GraphViz (1 member)
- Graphics (3 members)
- Gratis (1 member)
- Gravatars (1 member)
- Greens (2 members)
- Greg Maxwell (2 members)
- Grinders (1 member)
- Guerilla preservation (3 members)
- H. Margaret Wilson (2 members)
- HTML (4 members)
- HTTP (1 member)
- Hacking (3 members)
- Hamilton Hill (4 members)
- Hamilton Road (1 member)
- Hand planes (1 member)
- Hand tools (1 member)
- Handtools (1 member)
- HaveAnAdventure (2 members)
- Hcard (1 member)
- Heritage (6 members)
- Heritage interpretation (2 members)
- Hierarchies (1 member)
- Hiking (2 members)
- Hilton (2 members)
- Hipocracy (2 members)
- History (6 members)
- History of West Australia (1 member)
- Honesty (1 member)
- Hosting (3 members)
- Housemates (2 members)
- Houses (4 members)
- How I write (6 members)
- How Proust Can Change Your Life (1 member)
- Hush (1 member)
- Hyperlinks (2 members)
- Hypertext (2 members)
- I'm Sorry I Haven't A Clue (1 member)
- I.T. (1 member)
- IA Upload (2 members)
- IBM (7 members)
- ICT (2 members)
- ISAD(G) (1 member)
- ISOC (2 members)
- Identity (2 members)
- Category:Image Flicker plugin (0 members)
- Image Flicker plugin (4 members)
- Images (2 members)
- Imagination (2 members)
- Importing (4 members)
- InDesign (2 members)