The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Onyx Actions (1 member)
- Onyx Characters (0 members)
- Onyx Non-Player Characters (2 members)
- Onyx Vessels and Facilities (4 members)
- Orders (9 members)
- Organizations (2 members)
- Pages generating RSS feeds (0 members)
- Pages monitored by Wikipedia bots (1 member)
- Pages related to the WikiProject meta banner (1 member)
- Pages used in system messages needing protection (3 members)
- Pages using deprecated source tags (3 members)
- Pages using duplicate arguments in template calls (8 members)
- Pages with Issues (0 members)
- Pages with broken file links (0 members)
- Pages with incorrectly transcluded templates (1 member)
- Pages with script errors (52 members)
- People (127 members)
- Personal life (0 members)
- Personality traits (1 member)
- Philosopher navigational boxes (2 members)
- Philosophy and thinking navigational boxes (3 members)
- Philosophy and thinking sidebar templates (3 members)
- Philosophy of life (1 member)
- Places (48 members)
- Planes of Existence (13 members)
- Played by Amis (3 members)
- Played by BROK3N (5 members)
- Played by Bucket (9 members)
- Played by Chanree (5 members)
- Played by Cybersans (1 member)
- Played by Cyberstar (11 members)
- Played by Cyclops (69 members)
- Played by Darktrooper501 (0 members)
- Played by Dasfier (64 members)
- Played by Haladur phox (10 members)
- Played by Ice (1 member)
- Played by Icywinterdawn (0 members)
- Played by JumpingScript (13 members)
- Played by Ks0908 (25 members)
- Played by Kuroneo (3 members)
- Played by Left4Cake (6 members)
- Played by Lilith Aria Hyde (21 members)
- Played by Necahual (10 members)
- Played by Neo Akazuli (0 members)
- Played by NigrantibusAlis (2 members)
- Played by Ryu Ketsueki (1 member)
- Played by Ryu ketsueki (0 members)
- Played by Spartan889 (13 members)
- Played by The Chubby Gamer (4 members)
- Played by Timot1066 (13 members)