The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Transport infobox templates (1 member)
- Transportation Locations (1 member)
- Transportation infrastructure operated by the NEG (3 members)
- Travelnet hubs (1 member)
- Tutorial (3 members)
- Tutorials (5 members)
- Typing-aid templates (6 members)
- Uncategorized Tutorials (3 members)
- Unicode character modules (1 member)
- Unicode data modules (8 members)
- Unicode templates (1 member)
- Uses TemplateStyles templates with errors (1 member)
- Varieties of English templates (1 member)
- WikiProject Mountains templates (1 member)
- WikiProject Short descriptions (1 member)
- Wikipedia Portal templates (1 member)
- Wikipedia XHTML tag-replacing templates (7 members)
- Wikipedia article titles (2 members)
- Wikipedia categorization (1 member)
- Wikipedia formatting and function templates (2 members)
- Wikipedia formatting templates (1 member)
- Wikipedia infoboxes (1 member)
- Wikipedia magic word templates (2 members)
- Wikipedia maintenance (1 member)
- Wikipedia maintenance templates (1 member)
- Wikipedia metatemplates (8 members)
- Wikipedia multilingual support templates (2 members)
- Wikipedia non-diffusing parent categories (2 members)
- Wikipedia page-section templates (3 members)
- Wikipedia see also (2 members)
- Wikipedia self-reference templates (1 member)
- Wikipedia soft redirected templates (2 members)
- Wikipedia soft redirects (2 members)
- Wikipedia soft redirects to nonexistent targets (4 members)
- Wikipedia substituted templates (11 members)
- Wikipedia template categories (2 members)
- Wikipedia transclusionless templates (2 members)
- Wikipedia utility templates (7 members)
- Wikitext processing templates (1 member)
- Wikitext typing-aid templates (5 members)
- World Map (1 member)
- Writing system templates (1 member)
- 公共转换组模块 (2 members)
- 内部链接模板 (1 member)
- 字詞轉換模板 (4 members)
- 摺疊模板 (1 member)
- 放置于模板的noteTA (8 members)
- 电子游戏公共转换组模板 (1 member)
- 維基字詞轉換 (1 member)
- 维基百科元模块 (1 member)