List of fictional alien species: A

• 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
Aaamazzarite	Star Trek	Hairless humanoids that create objects biochemically from their mouths
Aalaag	Gordon R. Dickson's Way of the Pilgrim
Abh	Crest of the Stars	Genetically-enhanced humans
Abductors	Invader Zim, Squee
Abzorbalof	Doctor Who	Human-absorbing humanoid
Abyormenites	Hal Clement's Cycle of Fire	floating balloons
Acamarian	Star Trek
Acquarans	Farscape	Humanoid
Adipose	Doctor Who	Tiny, round humanoids made of fat
Advent	Sins of a Solar Empire	Humanoid
Advents (aka Uranus or the Creators)	Guyver: The Bioboosted Armor
Aenar	Star Trek	Telepathic humanoid
Aeodronians	Battlelords of the 23rd Century
Affront	Iain M. Banks' Excession
Agorian	Ratchet & Clank
Akaali	Star Trek
Akrennians	Titan A.E.	Rat/hyena-like humanoids who apparently do not dream (or bathe much); the character Preed is an Akrennian. The food "Akrennian Beetle Sushimi" is also featured in the film, hinting that insect-like life-forms are also found on their home planet.
Akritirians	Star Trek
Albategna	The webcomic Not So Distant	Large black-and-white creatures with six tentacular limbs (two for walking and four for manipulating)
The Alien	Satyajit Ray's The Alien and Banku Babu's Friend
Alien	The Hidden and its sequel	Parasitic and having the capability to possess its host
Alien Sex Goddesses	Church of the SubGenius
Alkari	Master of Orion
Allasomorph	Star Trek
Amaut	C. J. Cherryh's Alliance-Union universe
Altarians	Galactic Civilizations	Humanoid
Amazonians	Futurama	Giant humanoid women. Men of this species have died out.
Amnioni	Stephen Donaldson's The Gap Cycle	Humanoid
Amorphs	Schlock Mercenary
Anabis	The Voyage of the Space Beagle by A. E. van Vogt
Ancients	Farscape
Ancients	Freespace	Technologically advanced beings that were wiped out several thousand years ago. Unknown physical description.
Ancient	Stargate SG-1	Humans from Earth, with a developed intelligence, who in the age of the creation of the pyramids, left Earth for universe exploration.
Andalites	K. A. Applegate's Animorphs	Centaur-like, with non-poisonous scorpion tails, and blue fur
Andorians	Star Trek	Humanoid with blue skin, white hair, antennae
Andromeni	Battlelords of the 23rd Century
Angol Mois	Sgt. Frog
Angosians	Star Trek
Anodite	Ben 10 Alien Force
Antarans	Master of Orion II	Marauders exiled to a pocket dimension
Antarians	Imperium Galactica II: Alliances
Antedeans	Star Trek
Anterians	The Suite Life on Deck
Anticans	Star Trek
The Anti-Monitor	DC Comics
Aqualish	Star Wars
Aquatoids	X-COM: Terror from the Deep
Arachnids	Battlelords of the 23rd Century
Arachnoids	Serious Sam: The First Encounter	Scorpion-like
Aras	Perry Rhodan
Arbryls	Ascendancy
Arburian Pelarota	Ben 10
Arcadians	Star Trek
Arceans	Galactic Civilizations
Arcturians	Star Trek
Argolin	Doctor Who	Humanoid
Arilou Lalee'lay	Star Control	Humanoid - 'Grey' alien
Arisians and Eddorians	E. E. Smith's Lensman novels
Ark Megaforms	Noon Universe
Arkonides	Perry Rhodan
Armada of Annihilation	Axelay
Arquillians	Men in Black
Airlia	Area 51 novel series by Robert Doherty	Humanoid, see moai
Arnor	Galactic Civilizations II: Dread Lords
Asari	Mass Effect	Blue-skinned feminine humanoids
Aschen	Stargate SG-1	Humanoid
Asgard	Stargate SG-1	Grey humanoid
Aslan	Traveller RPG	Feline humanoid
Asuran	Stargate Atlantis
Atavus	Earth: Final Conflict	Humanoid
Atevi	C. J. Cherryh's Foreigner series	Tall, dark, mysterious humanoids. Culture progresses rapidly from steam-age to contemporary and beyond perhaps due to their numerological language. Assassin's Guild rather than police.
Aurelians	Advent Rising
Autobot	Transformers	A machine race that can transform between a humanoid form and that of a certain machine, depending on the specific Autobot
Auronar	Blake's 7
Autons	Doctor Who	Living plastic beings
Axanars	Star Trek
Axons	Doctor Who
Azathoth	Cthulhu Mythos
Azgonians	Perry Rhodan
Aziam	Battlelords of the 23rd Century