Kadhrein - Geoff Eddy

Kæseran - Alex Alfaro

Kagizerin - Nik Taylor

Kahan - Van Anderson

Kakarak - Kaurpin

Kalaba-X - Kenneth L. Pike

Kaldon - Warmaster

Kali-sise - Jeffrey Henning

Kaliso - Jashan

Kalonese - David J.S. Boyle

Kamakawi - David J. Peterson

Kankonian - James E. F. Landau

Kansu - Dan Morrison

Kardasi - Esther Schrager

Kardasi - Timothy Miller

Kardii - Jayelinda Suridge

Karis - Maknas

Karklak - Jeffrey Henning

Kar Marinam - Josh Roth

Kash - Roger Mills

Katari - Jeff Vedvik

Kattoelai - J.T. Antley

Kaupelanese - Paulo Eduardo França Padilha

Káyasánoda - Clint Jackson Baker

Keadaa muil - Aslan Majas

Kebreni - Mark Rosenfelder

Keki

Kel - Robert Jung

Keldare - Wyvere

Kélen - Sylvia Sotomayor

Kelenala - David J. Peterson

Kemilas - Robert L. Brown III

Keolah's Languages - Albrynnian, Andan, Hlayan, Kai'shanar, Katanic, Kishar, Margadian,

Kerinidoi - Drydic_Guy

Kerno - Padraic Brown

Kesh - Ursula K. Le Guin

Khangaþyagon - Pete Bleackley

Khikeng - Apollo Hogan

Khul

Khundruzn - Nicole Perrin

Khurwich

Khuzdul - J.R.R. Tolkien

Khuzdul, Neo- - J.R.R. Tolkien, David Salo

Kiadin - DarkHorizon

Kiffish - C.J. Cherryh; Spence Hill

Kika Olelo - Eclipse/Turquoise

Kimva - Pete Bleackley

kimwa lilyeho - Alex Fink

Kine - Daniel Myers

Kinfa - Sven Lotz

Kingfa - Apollo Hogan

Kingifa - Pete Bleackley

Kingiwa 'Awiwasa - Alex Fink

Kìn-Sang - Kári Emil Helgason

Kinsi Rorotan - Robert Wilson

Kinya - Maurizio Gavioli

Kioshu - Jeff Goguen

Kir - Jashan A'al

Kirda-han - Shane Hampton

Kirezagi - Herman Miller

Kiromi - Raphael Singing Wolf

Kirumb - Muke Tever

Klaatu's Language - Edmund H. North

Klingon - James Doohan, Marc Okrand

Klingonaase - John M. Ford

Knarwaz - Pablo Flores

KNSL - David J. Peterson

Koalìns - Rory

Kobaïan - Christian Vander

KOD - Johann Vielberth

Ko e Vagahau he Motu - Philip Newton

Ko'ilidel - Wyvere

Kokipopi - Eric Sleator McGill

kolaqadock - martin

Kon'ya - Larry Sulky

Kordron - Jeffrey Henning

Kor'ekhani - J. Matthew Saunders

Korpesk - Shawn C. Knight

Kosi - Robert Jung

Kosmal Idioma - José Guardiola

Kot - Bucchianeri Marco

Kótèsä - Justin Spahr-Summers

Kramxelian - Dtsdesign

Kriegsprach - Jeffrey Henning

Krithnag - Alex Middleton

Kronokayjin - Tyler Hogan

Ksokish

Kugzogak - Tom Killingbeck

Kupo

Kushan - Rob H.

Kusthü

Kûtêruûknêtîmû (Terpish) - Eddy the Great

Kvaaplaang - Tom Curtis

Kwaadakw - Victor Medrano

Kwendyngu - Ceisiwr Serith

Kya'terrian - Dtsdesign

Kyldil - Wyvere

Kyran - Kian

Kzinti - Roger Kuiper (and Man-Kzin Wars authors)