The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Pages using invalid self-closed HTML tags (1 member)
- Pages with broken file links (2 members)
- People (2 members)
- Portal templates (10 members)
- Projectiles (2 members)
- Research projects (1 member)
- Screenshots (12 members)
- Stubs (22 members)
- Template documentation (13 members)
- Templates (20 members)
- Templates with bad documentation (0 members)
- Templates with no documentation (0 members)
- The Bureau: XCOM Declassified (10 members)
- The Bureau: XCOM Declassified images (2 members)
- The Bureau armor (0 members)
- The Bureau enemies (1 member)
- The Bureau equipment (3 members)
- The Bureau gameplay (1 member)
- The Bureau locations (0 members)
- The Bureau missions (0 members)
- The Bureau projectiles (0 members)
- The Bureau weapons (0 members)
- UFO: Enemy Unknown (3 members)
- UFO: Enemy Unknown enemies (3 members)
- UFO: Enemy Unknown images (3 members)
- Unattributed files (0 members)
- User groups (12 members)
- User images (1 member)
- Utility templates (1 member)
- Weapons (2 members)
- Wiki maintenance (12 members)
- Wiki skin images (24 members)
- XCOM (4 members)
- XCOM: Enemy Unknown (12 members)
- XCOM: Enemy Unknown abilities (1 member)
- XCOM: Enemy Unknown armor (8 members)
- XCOM: Enemy Unknown concept art (2 members)
- XCOM: Enemy Unknown enemies (6 members)
- XCOM: Enemy Unknown equipment (3 members)
- XCOM: Enemy Unknown images (17 members)
- XCOM: Enemy Unknown locations (1 member)
- XCOM: Enemy Unknown missions (2 members)
- XCOM: Enemy Unknown projectiles (3 members)
- XCOM: Enemy Unknown research projects (10 members)
- XCOM: Enemy Unknown weapons (19 members)
- XCOM 2 (1 member)
- XCOM 2: War of the Chosen (3 members)
- XCOM 2: War of the Chosen characters (2 members)
- XCOM 2 War of the Chosen (7 members)
- XCOM Wiki (9 members)