| Work | Description | Characters |
|---|---|---|
| Mass Effect | 2007 video game | 3 |
| Mass Effect 2 | 2010 video game | 4 |
| Mass Effect 2: Lair of the Shadow Broker | 2010 downloadable content | 1 |
| Mass Effect 3 | 2012 video game | 4 |
| Mass Effect Galaxy | 2009 video game | 1 |
| Master and Apprentice | novel by Claudia Gray | 1 |
| Masters of the Universe | American media franchise | 1 |
| Matilda | 1996 American fantasy film by Danny DeVito | 1 |
| Matilda | 1988 children's book by Roald Dahl | 1 |
| Matilda the Musical | 2011 musical | 1 |
| Max Payne | 2008 film by John Moore | 1 |
| Max Payne | 2001 third-person shooter video game | 1 |
| Max Payne 2: The Fall of Max Payne | 2003 video game | 1 |
| Max Payne 3 | 2012 video game | 1 |
| Mean Girls | Musical based on the 2004 film Mean Girls | 1 |
| Mean Girls | 2004 American teen comedy film directed by Mark Waters | 5 |
| Megamind | 2010 American 3D computer-animated superhero comedy film directed by Tom McGrath | 2 |
| Megamind | 2010 video game | 2 |
| Megamind: Mega Team Unite | 2010 video game | 2 |
| Megamind: The Button of Doom | 2011 film by Simon J. Smith | 1 |
| Melora | episode of Star Trek: Deep Space Nine (S2 E6) | 7 |
| Memento | 2000 film by Christopher Nolan | 1 |
| Memoirs of a Geisha | 2005 film by Rob Marshall | 3 |
| Memory Prime | 1988 book by Judith and Garfield Reeves-Stevens from Pocket Books, from 1988 from United States of America | 5 |
| Mere Mortals | Book by David Alan Mack, from 2008 | 14 |
| Merlin | British fantasy-adventure television programme | 2 |
| Merry Madagascar | 2009 film directed by David Soren | 1 |
| Metal Gear | video game series | 3 |
| Metal Gear 2: Solid Snake | video game | 1 |
| Metal Gear Solid | 1998 adventure video game | 1 |
| Metal Gear Solid 2: Sons of Liberty | 2001 video game | 1 |
| Metal Gear Solid 3: Snake Eater | action-adventure stealth video game released in 2004 | 1 |
| Metal Gear Solid 4: Guns of the Patriots | action-adventure stealth video game | 2 |
| Metal Gear Solid: Peace Walker | 2010 video game | 1 |
| Metal Gear Solid V: Ground Zeroes | 2014 video game | 1 |
| Metal Gear Solid V: The Phantom Pain | 2015 open world action-adventure stealth video game | 2 |
| Metamorphoses | narrative poem by Ovid | 1 |
| Metamorphosis | Book by Jean Lorrah | 6 |
| Mickey and the Beanstalk | 1947 segment from Disney's Fun and Fancy Free directed by Hamilton Luske | 1 |
| Mickey, Donald, Goofy: The Three Musketeers | 2004 animated film film directed by Donovan Cook | 3 |
| Mickey's Grand Opera | 1936 film by Wilfred Jackson | 1 |
| Mickey's House of Villains | 2002 film by Tony Craig, Rick Schneider | 1 |
| Mickey's Once Upon a Christmas | 1999 animated Disney film | 4 |
| Mid Morning Matters with Alan Partridge | British comedy programme | 1 |
| Midrash Rabba | part of or the collective whole of specific aggadic midrashim on the books of the Torah and the Five Megillot | 1 |
| Midsomer Murders | British television detective drama series, aired on ITV since 1997, based on books by Caroline Graham | 1 |
| Mieruko-chan | Japanese anime television series | 1 |
| Mieruko-chan | Japanese manga series | 1 |
| Mike's New Car | 2002 animated short film | 2 |
| Millennium | series of novels by Stieg Larsson and David Lagercrantz | 2 |
| Minami-ke | Japanese manga series | 1 |
| Minami-ke | Japanese anime television series | 1 |
| Mindhunter | comic book | 1 |
| Mindhunter | 2017–2019 American television series | 4 |
| Mindscape | Mission in Star Trek: Online | 1 |
| Miraculous catch of fish | two miracles of Jesus | 1 |
| Miraculous: Tales of Ladybug & Cat Noir | French animation series | 4 |
| Mirai of the Future | 2018 film directed by Mamoru Hosoda | 1 |
| Misery | novel by Stephen King | 1 |
| Misery | 1990 film directed by Rob Reiner | 1 |
| Misfits | television series | 1 |
| Mission to Horatius | book by Mack Reynolds | 8 |
| Mitsudomoe | Japanese anime television series | 1 |
| Mitsudomoe | Japanese manga series | 1 |
| MM! | Japanese manga series | 1 |
| MM! | Japanese anime television series | 1 |
| MM! | Japanese light novel series | 1 |
| Moana | 2016 computer animated film produced by Walt Disney Animation Studios | 2 |
| Mobile Suit Gundam | Japanese anime television series | 1 |
| Mob Psycho 100 | Japanese anime television series | 8 |
| Mob Psycho 100 | Japanese web manga series | 5 |
| Mockingjay | 2010 book by Suzanne Collins | 3 |
| Modern Family | American comedy TV series | 15 |
| Modern Warfare 2: Ghost | Comic book mini-series | 1 |
| Moïse et Pharaon | opera by Gioachino Rossini | 1 |
| Moist Vessel | episode of Star Trek: Lower Decks | 1 |
| Mom's Got a Date with a Vampire | 2000 television film directed by Steve Boyum | 1 |
| Money Heist | Spanish television crime series | 4 |
| Money Shot: The Pornhub Story | 2023 film directed by Suzanne Hillinger | 1 |
| Monk | American television series | 2 |
| Monkey | 1978–1980 Japanese TV series | 1 |
| Monogatari | Japanese anime television series | 2 |
| Monogatari | Japanese light novel series | 3 |
| Monster | 1994 manga series by Naoki Urasawa | 7 |
| Monster | Japanese anime television series | 2 |
| Monster High | web series | 3 |
| Monster High | American fashion doll franchise | 2 |
| Monster Musume | Japanese manga series | 1 |
| Monster Musume | Japanese anime television series | 1 |
| Monsters at Work | American animated television series | 1 |
| Monsters, Inc. | video game | 2 |
| Monsters, Inc. | 2001 American computer-animated comedy film directed by Pete Docter | 2 |
| Monsters, Inc. Laugh Floor | attraction within the Magic Kingdom, a theme park at Walt Disney World Resort | 1 |
| Monsters, Inc. Mike & Sulley to the Rescue! | dark ride at Disney California Adventure | 1 |
| Monsters, Inc. Ride & Go Seek | 1 | |
| Monsters, Inc. Scream Arena | 2002 video game | 2 |
| Monsters, Inc. Scream Team | 2001 video game | 2 |
| Monsters University | 2013 American animated film directed by Dan Scanlon | 2 |
| Monthly Girls' Nozaki-kun | Japanese manga series | 1 |
| Monthly Girls' Nozaki-kun | Japanese anime television series | 1 |