The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Unapproved (3 members)
- Unassigned Solas Tempus Vessels and Facilities (24 members)
- Unexplained Artifacts (55 members)
- Unexplained Entities (46 members)
- Unexplained Events (9 members)
- United Federation of Planets Territory (2 members)
- Update Required (2 members)
- Vamelos Sector (2 members)
- Vampire Characters (12 members)
- Vehicle Specifications (0 members)
- Velastrion Sector (1 member)
- Vident Obscura Characters (1 member)
- WikiProject Music templates (1 member)
- WikiProject Philosophy templates (1 member)
- WikiProject banner templates (2 members)
- Wikipedia CatAutoTOC (2 members)
- Wikipedia categories named after ideologies (1 member)
- Wikipedia citation administration (1 member)
- Wikipedia editor help (1 member)
- Wikipedia formatting and function templates (2 members)
- Wikipedia infoboxes (1 member)
- Wikipedia metatemplates (1 member)
- Wonara Sector (2 members)
- XIA Characters (1 member)
- XIA Non-Player Characters (9 members)
- Xenoda Sector (7 members)
- Xi Ursae Sector (2 members)
- Z-6 Sector (2 members)