The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Aopoa (5 members)
- Apache License (5 members)
- Apartment Habs (4 members)
- Apocalypse Arms (15 members)
- Apocalypse Arms images (1 member)
- Apollo Images (2 members)
- Apollo Medivac images (16 members)
- Apollo Triage images (16 members)
- Apollo series (2 members)
- Aponte Explorer images (1 member)
- Appliance manufacturers (1 member)
- Appointment Missions (4 members)
- April Fool's (5 members)
- Ar (0 members)
- Ar-2 (0 members)
- ArcCorp (21 members)
- ArcCorp (planet) (1 member)
- ArcCorp AO Missions (13 members)
- ArcCorp images (29 members)
- Archangel Station images (1 member)
- Architecture images (22 members)
- Archon Base images (21 members)
- Arclight images (20 members)
- Arden-CL Backpack images (3 members)
- Arden-SL Helmet images (1 member)
- Arden-SL images (5 members)
- Arden-SL set (5 members)
- Area18 (3 members)
- Area18 images (110 members)
- Area 18 (3 members)
- Areas (1 member)
- Aremis (1 member)
- Aremis Post (0 members)
- Aremis images (4 members)
- Ares Inferno Images (2 members)
- Ares Inferno images (84 members)
- Ares Ion images (35 members)
- Ares inferno images (1 member)
- Ares series (2 members)
- Argo Astronautics (8 members)
- Argo Series (0 members)
- Argus Helmet images (1 member)
- Arial (2 members)
- Arial images (19 members)
- Aril Helmet images (1 member)
- Aril images (10 members)
- Aril set (5 members)
- ArmaMod (21 members)
- Armitage (planet) (1 member)
- Armor Shops (1 member)