The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Under Construction (103 members)
- Units (1 member)
- Unix (52 members)
- Urban Legends (6 members)
- UseMod (3 members)
- VRML (3 members)
- Veritas (1 member)
- Voice (11 members)
- Vollmondtage (13 members)
- VxVM (1 member)
- Wallpapers (1 member)
- Web (3 members)
- Webdesign ? (1 member)
- Websites (132 members)
- Wiki (237 members)
- WikiCulture (1 member)
- Wiki Calendar (2 members)
- Wiki hives (9 members)
- Wikilandia (6 members)
- Wikimania (2 members)