The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Aliens (28 members)
- Allies (7 members)
- Article management templates (5 members)
- Article stubs (62 members)
- Articles that need improvement (11 members)
- Black Mesa (3 members)
- Black Ops (3 members)
- BlogListingPage (0 members)
- Blog posts (0 members)
- Bosses (7 members)
- Browse (2 members)
- Campaigns (0 members)
- Candidates for deletion (0 members)
- Category templates (3 members)
- Community (5 members)
- Content (4 members)
- Copyright (0 members)
- Disambiguations (0 members)
- Enemies (46 members)
- Entities (34 members)
- Forums (6 members)
- General wiki templates (30 members)
- Guides (4 members)
- HECU (5 members)
- Help (5 members)
- Help desk (2 members)
- Hidden categories (2 members)
- Image wiki templates (9 members)
- Images (6 members)
- Infobox templates (7 members)
- Machines (5 members)
- NPCs (41 members)
- New pages (0 members)
- Organisation (0 members)
- Organization (8 members)
- Pages with broken file links (3 members)
- Policy (2 members)
- SC Weapons (5 members)
- Site administration (3 members)
- Site maintenance (4 members)
- Sven Co-op (5 members)
- Tab Templates (1 member)
- Template Documentation (1 member)
- Template documentation (64 members)
- Templates (11 members)
- Vehicles (4 members)
- Videos (15 members)
- Watercooler (2 members)
- Weapons (30 members)