The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Black Engines (6 members)
- Blog posts (0 members)
- Blue Engines (10 members)
- Brown Engines (1 member)
- Candidates for deletion (0 members)
- Characters (62 members)
- Cherry Engines (1 member)
- Community (1 member)
- Cream Engines (1 member)
- Creators (1 member)
- Diesel Engines (12 members)
- Disambiguations (0 members)
- Documentation templates (1 member)
- Electric Engines (2 members)
- Episodes (21 members)
- Female characters (15 members)
- Filmmakers (6 members)
- Fire and Rescue Service Engines (1 member)
- Former Voice Actors (2 members)
- General wiki templates (18 members)
- Green Engines (12 members)
- Hatnote templates with errors (0 members)
- Humans (46 members)
- Image license templates (13 members)
- Images (4 members)
- Infobox templates (13 members)
- International Engines (2 members)
- Lavender Engines (1 member)
- Light Blue Engines (1 member)
- Locations (1 member)
- Mainland Engines (1 member)
- Maintenance (6 members)
- Male characters (42 members)
- Marron Engines (4 members)
- Media (2 members)
- NWR Adventures (22 members)
- NWR Adventures Series Wiki (6 members)
- Narrow Gauge Engines (9 members)
- Navbox templates (1 member)
- Notice templates (10 members)
- Orange Engines (2 members)
- Orche Engines (2 members)
- Original Characters (21 members)
- Pages with broken file links (0 members)
- Purple Engines (1 member)
- Quote templates (2 members)
- Railway Police Engines (1 member)
- Red Engines (11 members)
- Rolling Stock (1 member)
- Screenshots (0 members)
- Season 1 (17 members)
- Season 2 (2 members)
- Season 3 (2 members)
- Season 4 (1 member)
- Silver Engines (1 member)
- Steam Engines (52 members)
- Steam Trams (2 members)
- Stubs (0 members)
- Tank Engines (30 members)
- Template documentation (56 members)
- Templates (11 members)
- Tender Engines (22 members)
- The Golden Girls (5 members)
- The Steam Team (21 members)
- Tram Engines (4 members)
- Trucks (1 member)
- Twins (1 member)
- Unattributed files (0 members)
- Videos (0 members)
- Voice Actors (47 members)
- Wiki skin images (2 members)
- Writers (1 member)
- Yellow Engines (6 members)