The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Morechand (3 members)
- Mori,Toshimichi (1 member)
- Mori, Toshimichi (269 members)
- Mori P (90 members)
- Mother (4 members)
- Motomura, Junya (3 members)
- Mouse Pads (7 members)
- Mu-12 (374 members)
- Mucro Algesco: Yukianesa (34 members)
- Mucro Somnio: Musashi (3 members)
- Mukai (0 members)
- Mukai, Katsuki (21 members)
- Mumei (1 member)
- Murakami (1 member)
- Murakumo Units (3 members)
- Muramatsu, Katsura (5 members)
- Music (2 members)
- Music Albums (25 members)
- Music templates (1 member)
- Mutsuki (5 members)