The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- ADP images (1 member)
- ADP set (4 members)
- ARC-L1 Wide Forest Station images (1 member)
- ARC-L1 images (1 member)
- ARC-L2 images (1 member)
- ARC-L3 images (1 member)
- ARC-L4 images (1 member)
- ARC-L5 images (1 member)
- ARGO Astronautics (0 members)
- ATVS Repeater images (1 member)
- AVS-E set (2 members)
- A Human Perspective (0 members)
- A Separate Law (0 members)
- Abbreviations (51 members)
- Aberdeen (5 members)
- Aberdeen images (23 members)
- Ace Astrogation (4 members)
- Aciedo Station images (1 member)
- Active Duty Military Characters (54 members)
- Active Political Office Holders (34 members)