The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Modules subject to page protection (1 member)
- Molière (1 member)
- Multi-column templates (1 member)
- Music (64 members)
- NMAC 3108 (32 members)
- NMAC 3900 (2 members)
- NMAC 3999 (3 members)
- NMAC 4460 (46 members)
- NMAC 4483 (2 members)
- NMAC 5108 (18 members)
- Namespace manipulation templates (3 members)
- Nathaniel Hawthorne (2 members)
- Navboxes using background colours (16 members)
- Navigational boxes (1 member)
- Navigational boxes without horizontal lists (3 members)
- Neal Asher (2 members)
- Neal Stephenson (3 members)
- New Media (114 members)
- News (1 member)
- Nighthawk (35 members)
- Nikkor 2/35 (4 members)
- Nikolai Gogol (0 members)
- Noindexed pages (2 members)
- Nokton 1.5/50 (3 members)
- Nokton Classic 1.4/40 (42 members)
- Norman Mailer (118 members)
- Norman Mailer Society (69 members)
- Nostalgia (22 members)
- Notes (10 members)
- Octavia Butler (2 members)
- Olaf Stapledon (1 member)
- Olympus OM-2N (23 members)
- Online (39 members)
- OpenWrt (3 members)
- Organization (FAQ) (15 members)
- Orson Scott Card (0 members)
- Oscar Wilde (1 member)
- Ovid (14 members)
- POD (131 members)
- Pages used in system messages needing protection (3 members)
- Pages using deprecated source tags (2 members)
- Pages using div col with small parameter (1 member)
- Pages with broken file links (2 members)
- Pages with ignored display titles (4 members)
- Pages with non-numeric formatnum arguments (1 member)
- Pages with script errors (55 members)
- Pages with short description (155 members)
- Pages with syntax highlighting errors (26 members)
- Parameter handling templates (1 member)
- Partially Online (1 member)