List of fictional alien species: M

• A
• B
• C
• D
• E
• F
• G
• H
• I
• J
• K
• L
• M
• N
• O
• P
• Q
• R
• S
• T
• U
• V
• W
• X
• Y
• Z

Name	Source	Type
M-113 Creature	Star Trek
Macra	Doctor Who	Crustacoid
Magma	Ultraman Leo	Saber Tyrant
Magog	Andromeda
Magolor	Kirby's Return to Dream Land.
Mahendo'sat	C. J. Cherryh's Chanur novels
Maians	Perfect Dark
Majat	C. J. Cherryh's Alliance-Union universe
Malons	Star Trek
Mangalores	The Fifth Element	Thick-skinned humanoids; warriors and weapon specialists. Considered savage and brutish by other races.
Mantis	Conquest: Frontier Wars
Mantrins	Titan A.E.	Kangaroo-like aliens with large, powerful back legs; native to Solbrecht. The character Stith is a Mantrin. Also called Sogowans.
Marklars	South Park	Orange-skined aliens with egg-shaped heads and yellow eyes. They refer to all people, places, and things as "Marklar".
Marmosians	Ascendancy
Marro	Heroscape	Skinless creatures with insectoid social organization
Martians	H. G. Wells' The War of the Worlds
Martians	Edgar Rice Burroughs's Barsoom series	Humanoid
Martians	Marvin the Martian from Looney Tunes and Duck Dodgers
Martians	Premendra Mitra's Mangalbairi (The Martian Enemies)
Martians	Ray Bradbury's The Martian Chronicles	Humanoid
Martians	Aelita (1924 movie)	Humanoid
Martians	Mars Attacks (Topps trading cards) and Mars Attacks! (Tim Burton movie)	Humanoid
Martians	Quatermass and the Pit
Martians	Larry Niven's Known Space
Martian Manhunter	DC Comics
Marzoids	Invader Zim
Masari	Universe at War	A sentient race of ancient Atlantians that are human-like in appearance.
Masters	The Tripods
Mazians	Battlelords of the 23rd Century
Mebes	Ascendancy
Mechanon	Star Frontiers	sentient mechanical race created by the Eorna
Medusans	Star Trek
Meehooks	Fusion comic book series	dinosaurs with fur
Megawhatt	Ben 10
Meekrob	Invader Zim	Pure Enegy beings. Meekrob was set to be conquered by Invader Tenn until she received a shipment of malfunctioning SIR Units giving away her location and thus angering the Meekrob, creating further tension between the Meekrob and the Irken Empire.
Meklars	Master of Orion
Melconians	Keith Laumer's Bolo series	canine-like humanoids
Melmacians	ALF
Melnorme	Star Control
Melotians	Melonpool
Memory Donk	Bravest Warriors	The Memory Donks are a species of "old-lady"-like beings that take away the memory of anyone around them.
Menoptra	Doctor Who
Mentors	Doctor Who
Merseians	Technic History by Poul Anderson
Merewifs	Bravest Warriors	Merewifs are a race of mermaid-like creatures. Most notably, Plum
Mesklinites	Hal Clement's Mission of Gravity	millipede-like
Methorians	Barrington J. Bayley's Zen Gun	gaseous giant-giant dwellers
Metroid	Metroid series
Metrons	Star Trek
Micros	Brain Plague by Joan Slonczewski	Microbial aliens that inhabit the brain and offer their host new abilities.
Microman	Microman
Micronoids	X-Com: Apocalypse	Sentient parasitic bacteria
Minbari	Babylon 5	Humanoid
Minions	Ascendancy
Minosians	Star Trek
Mintakans	Star Trek
Miradorn	Star Trek
Misha	Battlelords of the 23rd Century	Humanoid
Mmrnmhrm	Star Control
Mon Calamari	Star Wars
Mondoshawan	The Fifth Element	Humanoid
Monoids	Doctor Who
Mogadorians	Lorien Legacies	Humanoid, warlike race intent on destroying the Loric and invade Earth. Described as having very pale skin and dark hair and eyes.
Moon Dragons	Bravest Warriors	Moon Dragon toenails are used to make the Bravest Warriors' space suits.
The Mooninites	Aqua Teen Hunger Force (individually: Igninokt and Err)
Mork	Mork and Mindy
Morlocks	H. G. Wells' The Time Machine
Morlocks	Larry Niven's Known Space
Moroks	Doctor Who	Humanoid
Mor-Taxans	War of the Worlds (TV series - first season)
Morthren	War of the Worlds (TV series - second season)
Movellans	Doctor Who
Moxx of Balhoon	Doctor Who	Humanoid
Mri	C. J. Cherryh's Faded Sun trilogy	Humanoid
Mr. Saturn	EarthBound
Mrrshan	Master of Orion
Mudokons	Oddworld series
Mugato	Star Trek
Mutons	X-COM: UFO Defense
Mutzachans	Battlelords of the 23rd Century	Humanoid
Muuh	Orion's Arm
Mycon	Star Control
The Mysterons	Captain Scarlet and the Mysterons