The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Advanced Trains Tutorials (1 member)
- Albums by Artist (1 member)
- Albums by John Oestmann (1 member)
- Article message templates (1 member)
- Article message templates with missing parameters (1 member)
- Articles (5 members)
- Articles containing Chinese-language text (3 members)
- Articles using infobox body of water without image bathymetry (1 member)
- Articles using infobox body of water without pushpin map (1 member)
- Articles with hatnote templates targeting a nonexistent page (3 members)
- Articles with short description (4 members)
- Buildings and structures infobox templates (2 members)
- Business infobox templates (1 member)
- Category namespace templates (8 members)
- Change History (1 member)
- Character-substitution templates (2 members)
- Character templates (2 members)
- Chest Tutorials (1 member)
- Collapse templates (3 members)
- Container categories (17 members)
- Contents (1 member)
- Conversion subtemplates (1 member)
- Convert-like templates (1 member)
- Convert by module documentation (1 member)
- Coordinates templates (1 member)
- Data Templates (1 member)
- Date-computing templates based on current time (1 member)
- Disambiguation and redirection templates (3 members)
- Disambiguation message boxes (2 members)
- Documentation assistance templates (2 members)
- Documentation header templates (4 members)
- Documentation see also templates (3 members)
- Documentation subpages without corresponding pages (1 member)
- Elevator Tutorials (1 member)
- Embeddable templates (5 members)
- Engvar (2 members)
- Error-handling modules (1 member)
- Error-message templates (1 member)
- File message boxes (1 member)
- File namespace templates (2 members)
- Fraction templates (1 member)
- GPL Templates (5 members)
- Hatnote modules (4 members)
- Hatnote templates (2 members)
- Header templates (1 member)
- Hidden categories (5 members)
- Highway infobox templates (1 member)
- If-then-else templates (1 member)
- Image with comment templates (7 members)
- Infobox modules (2 members)