The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Medical supplies (1 member)
- Medium (19 members)
- Medium- Bidirectional (1 member)
- Medium - Bidirectional (9 members)
- Medium backpacks (3 members)
- Medium ships (40 members)
- Mercenary Missions (32 members)
- Merchantman images (33 members)
- Mercury Star Runner Flight Jacket images (1 member)
- Mercury Star Runner images (148 members)
- Mercury Star Runner series (1 member)
- Mesoplanet (14 members)
- Messer Regimes (12 members)
- Meta templates (1 member)
- Metals (6 members)
- MicroTech (18 members)
- MicroTech (planet) (24 members)
- MicroTech AO Missions (8 members)
- MicroTech images (55 members)
- Microid Battle Suit images (1 member)
- Microid Battle Suit set (1 member)
- MicrotechAO Missions (1 member)
- Military (5 members)
- Military Characters (39 members)
- Military bases (1 member)
- Military computers (6 members)
- Military coolers (13 members)
- Military power plants (25 members)
- Military quantum drives (9 members)
- Military radars (8 members)
- Military shield generators (16 members)
- Million Mile High Club images (1 member)
- Min System (6 members)
- Mineables (23 members)
- Minerals (12 members)
- Minigames (1 member)
- Mining Laser Consumable (8 members)
- Mining Rocks (0 members)
- Mining gadget images (1 member)
- Mining gadgets (0 members)
- Mining laser (16 members)
- Mining laser heads (5 members)
- Mining modules (45 members)
- Mira Ngo images (1 member)
- Mirai (5 members)
- Miscellaneous (0 members)
- Miscellaneous items (15 members)
- Missile launchers (2 members)
- Missile racks (0 members)
- Missing production state (4 members)