The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- MacFlex set (5 members)
- Machine transcripts (1 member)
- Magazine (4 members)
- Magazines (63 members)
- Magda (2 members)
- Magda images (16 members)
- Magnus System (6 members)
- Main Sequence-Class-G (0 members)
- Main Sequence-Class-K (0 members)
- Main Sequence-Dwarf-G (1 member)
- Main Sequence-Dwarf-K (1 member)
- Main Sequence A-type (5 members)
- Main Sequence B-type (3 members)
- Main Sequence Dwarf-A (5 members)
- Main Sequence Dwarf-F (4 members)
- Main Sequence Dwarf-G (6 members)
- Main Sequence Dwarf-K (5 members)
- Main Sequence Dwarf-M (1 member)
- Main Sequence F-type (8 members)
- Main Sequence G-type (16 members)
- Main Sequence K-type (14 members)
- Main Sequence M-type (1 member)
- Main Sequence O-type (1 member)
- Main page templates (11 members)
- Mainpage images (22 members)
- Maintenance (1 member)
- Maintenance Missions (5 members)
- Maintenance templates (6 members)
- Male Characters (171 members)
- Male clothing (27 members)
- Male or Female Characters (1 member)
- Man-made (12 members)
- Mandible Helmet images (5 members)
- Mantis images (46 members)
- Mantis series (0 members)
- Manual templates (6 members)
- Maps (7 members)
- Markahil System (1 member)
- Markets (2 members)
- Mars (2 members)
- Mascots (4 members)
- Mass Driver Cannon (6 members)
- Mathematical function templates (7 members)
- MaxOx (5 members)
- Mechanics (2 members)
- MedPen images (1 member)
- Media (0 members)
- Media (lore) (9 members)
- Media lacking author information (2 members)
- Medical images (1 member)