List of fictional alien species: K

Name	Source	Type
	2300 AD	Humanoid
Kaleds	Doctor Who	Humanoid
Kalish	Farscape	Humanoid
Kaalium	Moontrap	Cyborg
Kal-Kriken	Utopia
Kalliran	C. J. Cherryh's Alliance-Union universe
Kambuchka	Ascendancy
Kanamit	To Serve Man Twilight Zone and Short Story	Humanoid
Kang and Kodos	The Simpsons	Squid-like. Green, single-eyed squids intent on conquering Earth
Karemma	Star Trek	Humanoid
Kariak	Haegemonia: Legions of Iron
Kat	Kid vs. Kat	cybernetic, cat-like alien
Kazon	Star Trek	Humanoid
Kdatlyno	Larry Niven's Known Space
	Sgt. Frog
Kess'Rith	Renegade Legion	reptilian rhino-like centauroid
Key-Guardians	Utopia
King Ghidorah	Godzilla films	Three-headed dragon
Kineceleran	Ben 10	Armored velociraptor-like humanoids from the stormy planet Kinet, Kinecelerans have extraordinary speed, able to accelerate to 500 miles per hour in a second. They can use their speed to generate twisters, and also have prehensile tails and sharp claws.
Kisshu	Tokyo Mew Mew
Kharaa	Natural Selection
	Wildstorm
Khunds	DC Comics	Humanoid
	Farscape	Humanoid
Kif	C. J. Cherryh's Chanur novels
	Halo
Kilaaks	Destroy All Monsters
Kilrathi	Wing Commander games
	Battlelords of the 23rd Century	Humanoid
	Earth: Final Conflict
King Cold	Dragon Ball Z	Humanoid; Reptilian
Kivar	Roswell
Klaestronian	Star Trek	The Federation visited the planet Klaestron in 2339 to mediate the Klaestronian Civil War. (DS9 episodes "Dax", "Second Skin")
Klackons	Master of Orion
	2300 AD
Kleer Skeleton	Serious Sam: The First Encounter
Klingons	Star Trek	Humanoid
Knnn	C. J. Cherryh's Chanur novels
Koozbanians	The Muppet Show
Korath	Galactic Civilizations II: Dark Avatar
Korbinites	Marvel Comics
Korvax	No Man's Sky	Humanoid; Machine
Korx	Galactic Civilizations: Altarian Prophecy
K-PAXians	K-PAX
Kra'hen	Imperium Galactica II: Alliances
	Battlelords of the 23rd Century
Kraylor	Star Trek	Humanoid
Kree	Marvel Comics	Humanoid
	Star Trek
Kreely	Schlock Mercenary
Kreetassan	Star Trek
Krell	Forbidden Planet
Krellepem	Harry Turtledove's Worldwar series	An aquatic animal native to Home. Their uncanny physiology resembled Earth's extinct trilobites and they were implied to be less evolved. Krellepem are treated as a delicacy by the Race in which special tools are required to break their shells, especially since the Race could not even suck the meat out of the shells as humans could do.
Krenim	Star Trek
Kriken	Metroid Prime Hunters
Krishnans	L. Sprague de Camp's Viagens Interplanetarias Series	Green skinned humanoids with antennae.
Krith	Richard C. Meredith's Timeliner Trilogy
Krogan	Mass Effect
Krolp	Harry Turtledove's Vilcacamba	Centauroids larger than horses with tiger-like stripes, heads similar in shape to a jack-o'-lantern with jagged jaws, and have a strong odor that similar in smell to Limburger cheese.
Kromaggs	Sliders
Kronn	Area 51 and its sequel	One-eyed insectoid. Able to mutate humans, turning them into zombies, cling on walls, and fires some sort of energy.
Kroot	Warhammer 40,000
Krynn	Galactic Civilizations II: Dark Avatar
	The Journeyman Project 2: Buried in Time
Krynoids	Doctor Who
Kryptonians	Superman	Humanoid
Kryten	Red Dwarf	Series 4000 Mechanoid
Kssthrata	Schlock Mercenary
K'tang	Star Control 3
Ktarian	Star Trek
	The Sinusoidal Spaghetti
Kweltikwan	Lilo & Stitch	Characterized by a large, rotund figure, four yellow eyes and a dark blue-ish/purple skin tones save for pink on their chest/stomachs, large wide mouths, blunted fangs and small noses.
Kymellians	Marvel Comics	Humanoid body with horses head
Kymera	Fortnite Battle Royale	Level 1 skin in the Chapter 2: Season 7 Battle Pass, very customizable.
	FTL:2448 RPG
Kyo	C. J. Cherryh's Foreigner series
Kyrie	Heroscape	Humans with wings
	O.R.B: Off-World Resource Base
Kzinti	Larry Niven's Known Space series and Star Trek: The Animated Series	Felinoid - large bi-pedal tigers. Male: Kzintosh, Female: Kzinrett. Aggressive space-faring carnivores, with sub-sapient females