The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- 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)
- In support of I.T. (1 member)
- Increments (1 member)
- Indexing (1 member)
- Indian Pacific (1 member)
- Indieweb (4 members)
- Information Technology (2 members)
- Inlaying (2 members)
- Installation (3 members)
- Integration tests (1 member)
- Intellectual property (1 member)
- Internet (6 members)
- Internet Archive (5 members)
- Internet Society (2 members)
- Investigation (10 members)