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- Marianne (Marianne) – Viktoria Sätter
- Stu Macher (Scream) - Matthew Lillard
- Mae (Near Dark) - Jenny Wright
- Horace Breaker Mahoney aka The Juggernaut (Thirteen Ghosts)
- Arthur Malcolm (The Headless Eyes) - Bo Brundin
- Carlos Malfeitor (Witchboard) - J.P. Luebsen
- Mary Lou Maloney (Hello Mary Lou: Prom Night II) - Lisa Schrage
- Leslie Vernon Mancuso (Behind the Mask: The Rise of Leslie Vernon) - Nathan Baesel
- George Markley aka The Hammer (Thirteen Ghosts)
- Man in the Mask (The Strangers) - Kip Weeks
- Maniac (Don't Go in the Woods) - Tom Drury
- Manuela (Bloody Moon) - Nadja Gerganoff
- Claude and Philip Markham (Cruel World) - Daniel Franzese and Edward Furlong
- Marko (The Lost Boys) - Alex Winter
- Leonard Marliston (Cherry Falls) - Jay Mohr
- Neil Marshall (Death Screams) - Martin Tucker
- Martin (Evil Laugh)
- Geraldine S. Masters (The Forgotten) - Annabelle Weenick
- Mary Mattock aka Mary Hatchet (Blood Night: The Legend of Mary Hatchet) - Samantha Facchi*
- Max (The Lost Boys)-(Edward Herrmann)
- David McCall (Fear) - Mark Wahlberg
- Andy McDermott (An American Werewolf in Paris) - Tom Everett Scott
- Johnny McFarley (The Paperboy) - Marc Marut
- Sean McIntyre (Death on Demand) - Jerry Broome
- Jennifer McKenzie (Red Riding Hood) - Susanna Satta
- Thorton Meeks (Mr. Brooks) - Matt Schulze
- Adam Meiks (Frailty) - Matthew McConaughey and Jeremy Sumpter
- Dad Meiks (Frailty) - Bill Paxton
- Fenton Meiks aka God's Hand Killer (Frailty) - Levi Kreis and Matt O'Leary
- Jeremy Melton/Adam Carr (Valentine) - David Boreanaz
- Billy Michaels aka The First Born Son (Thirteen Ghosts)
- Mike aka Stuntman Mike (Death Proof) – Kurt Russell
- Milk Maiden (2001 Maniacs) - Christa Campbell
- Reno Miller (The Driller Killer) - Abel Ferrara
- John Mills (Twisted) - Samuel L. Jackson
- Morty aka The Convenience Store Killer (Cornered!) - Steve Guttenberg
- Mother (Mother's Day) - Beatrice Pons
- Mr. Jingles (Mr. Jingles) - Dr. Rudy Hatfield
- Mr. Muldoon (Killer's Moon) - Paul Rattee
- Mr. Static (Demonic Toys and its sequels)
- Ms. Leech Woman (Puppet Master and its sequels)
- Carl Mueller (Sometimes They Come Back) - Don Ruffin and William Sanderson
- Michael Myers (the Shape) (Halloween and its sequels) - Nick Castle (masked), Tony Moran (unmasked), Will Sandin (age 6)
- Michael Myers (the Shape) (Halloween II and its sequels) - Dick Warlock, Adam Gunn (young Michael Myers), Tony Moran (archive footage)
- Michael Myers (Halloween (2007 remake) and its sequels) - Tyler Mane and Daeg Faerch (Michael Myers at age 10)
- Michael Myers (Halloween II and its sequels) - Tyler Mane and Chase Vanek (young Michael Myers)
Read more about this topic: List Of Horror Film Antagonists