The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Academic institutions (7 members)
- Academic institutions in England (4 members)
- Academic institutions in the United States (2 members)
- Academic organizations (1 member)
- Academics (51 members)
- Action games (26 members)
- Activities (13 members)
- Actors and actresses (398 members)
- Adaptation citation templates (19 members)
- Adaptations (20 members)
- Adaptations templates (12 members)
- Adjectives (4 members)
- Adventure games (18 members)
- Adverbs (2 members)
- Adûnaic (3 members)
- Adûnaic names (29 members)
- Adûnaic words (19 members)
- Affixes (5 members)
- Ages (17 members)
- Aiglos (journal) (6 members)
- Ainur (12 members)
- Ainur realms (3 members)
- Albums (58 members)
- Aliases (17 members)
- Aman (31 members)
- American businesses (47 members)
- American locations (2 members)
- American organizations (10 members)
- American people (365 members)
- American users (48 members)
- Amiga games (3 members)
- Amon Hen (journal) (303 members)
- Amstrad CPC games (11 members)
- Andustar (7 members)
- Angles (9 members)
- Anglicized Westron words (4 members)
- Anglo-Saxon pronunciations (1 member)
- Anglo-Saxons (15 members)
- Animals (52 members)
- Animals from adaptations (9 members)
- Annals (8 members)
- Apple II games (1 member)
- Apple II series games (12 members)
- Apple Macintosh games (7 members)
- Appledore (2 members)
- Arandor (7 members)
- Aratar (10 members)
- Arcade games (1 member)
- Arda (12 members)
- Arda issues (2 members)