The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Interwiki link templates (2 members)
- Java platform game (1 member)
- Jolly Roger flags with skull and crossbones (1 member)
- Knowledge representation (1 member)
- Language link templates (2 members)
- Language templates (2 members)
- Layout templates (12 members)
- Legendary creatures (2 members)
- Letters in blue circles (1 member)
- License tags attribution (3 members)
- License tags full-text (2 members)
- License tags of the United States (1 member)
- License tags share-alike (3 members)
- Life sciences (1 member)
- Linux video games by name (1 member)
- Localisation templates (2 members)
- Location not applicable (1 member)
- Logos of video games by name (1 member)
- MacOS video games by name (1 member)
- Magnifying glass icons (0 members)
- Magnifying glasses (1 member)
- Magnifying glasses in art (1 member)
- Main message boxes (17 members)
- Main topics (2 members)
- Maintenance data structures (3 members)
- Mammalia taxa by rank (1 member)
- Mammals by adaptation (1 member)
- Marine animals (1 member)
- Marine mammals (1 member)
- Marker templates (1 member)
- MediaWiki software tracking categories (4 members)
- Meta categories (1 member)
- Metacategories not fully sorted into flat categories (1 member)
- Metaphysics (1 member)
- Microsoft video games (1 member)
- Minecraft (0 members)
- Miocene first appearances (1 member)
- Models by type (1 member)
- Mojang Studios (1 member)
- Mollusca (0 members)
- Multi-template documentation (1 member)
- Multimedia icons (1 member)
- Musicians by name (1 member)
- Mythological characters (1 member)
- Mythological creatures (1 member)
- Navigation by country templates (1 member)
- Navigational boxes without horizontal lists (1 member)
- Navigational templates (1 member)
- Neomura (1 member)
- Nihon Ken (1 member)