The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Kawauchi, Daisuke (1 member)
- Kazuma Kval (211 members)
- Kecho (6 members)
- Keychains (38 members)
- Kiiro Hikagami (131 members)
- Kim, Hyung-tae (2 members)
- Kimura, Shigetaka (4 members)
- Kiri (29 members)
- Kisaragi (4 members)
- Kitchen Goods (21 members)
- Kokonoe (585 members)
- Konomi Higuchi (9 members)
- Kuon Glamred Stroheim (361 members)
- Kuroichigo, Kyo (18 members)
- Labrys (26 members)
- Lakeside Port (17 members)
- Lambda-11 (408 members)
- Lao Jiu (192 members)
- Legacy Weapon Wielders (6 members)
- Legacy Weapons (5 members)
- Lessons (8 members)
- Linhua (145 members)
- Linne (45 members)
- Litchi Faye-Ling (696 members)
- Lobby Avatars (509 members)
- Locations (75 members)
- Logos (95 members)
- Lord Stroheim (4 members)
- Lord of Vermilion (2 members)
- Lord of Vermilion III (9 members)
- Lord of Vermilion Re:2 (12 members)
- Lost: Memories Characters (28 members)
- Lost Town (21 members)
- Lotte Carmine (8 members)
- Lux Sanctus: Murakumo (7 members)
- Lycanthrope (2 members)
- Mabinogi Duel (55 members)
- Mage's Guild (12 members)
- Mages (25 members)
- Magic Guild (13 members)
- Magister's City -Ishana- (12 members)
- Mai Natsume (541 members)
- Main Artwork (160 members)
- Makoto Nanaya (876 members)
- Male Characters (49 members)
- Manga (13 members)
- Manga Illustrations (162 members)
- Mantenbo (6 members)
- Masuzawa, Hiroaki (8 members)
- Mayumi Tsuzaki (0 members)
- Media (74 members)
- Media Categories (20 members)
- Media by Artist (48 members)
- Media by Character (160 members)
- Media by Gallery Category (28 members)
- Media by Location (51 members)
- Media by Source (24 members)
- Media by Weapon (20 members)
- Media from Collaborations (8 members)
- Media from Events (17 members)
- Media from Manga (6 members)
- Media from Novels (12 members)
- Media of Crossover Locations (3 members)
- Media of Merchandise (868 members)
- Media of Merchandise by Source (0 members)
- Mei Amanohokosaka (276 members)
- Meifang Lapislazuli (131 members)
- Memory of BLUE Characters (4 members)
- Mercury (11 members)
- Merkava (27 members)
- Mika (27 members)
- Military Academy (12 members)
- Miscellaneous Merchandise (15 members)
- Mitsuru Kirijo (26 members)
- Mitsurugi Agency (13 members)
- Mobile Battle Characters (6 members)
- Mobile Games (4 members)
- Model Sheets (444 members)
- Mono (1 member)
- Monorail (7 members)
- 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)