Kallusians — A humanoid race first seen in Avengers #14 (Mar 1965).

Kamado — A humanoid race with an exaggeratedly muscular phyisque, first seen in Defenders #125 (Nov 1983).

Kawa — A reptilian semi-humanoid race with orange skin that averages 10′ in height, first seen in Hercules #3 (Nov 1982).

Klklk — An insectiod race covered with chtinous carapaces that averages 8′ in length from head to end of tail, first seen in The Incredible Hulk #273 (Jul 1982). “Insectoid Disease”?

Kodabaks — A humanoid porcine race with two digits on each appendage, averaging 6′2″ in height, first seen in Marvel Two-In-One Annual #2 (1977).

Korbinites — A humanoid race with light orange skin, averaging 6′2″ in height, and originating in the so-called “Burning Galaxy.” Beta Ray Bill is a Korbinite. First seen in Thor #337 (Nov 1983). “Inflammatory Disease” could apply here.

Kosmosians — A semi-reptilian race with similarities to multi-cellular amoeboids, with bodies that can “flow” as they move, thereby changing their length, which is 50′ on average. They have limited telepathic abilities which cause victims to be hypnotized into ceasing to live. Dr. Vernon van Dyne, father of Janet van Dyne once summoned a Kosmosian to Earth, which killed him; Henry Pym drove the creature away from Earth. First seen in Tales to Astonish #44 (Jun 1963).

Kronans — A semi-humanoid race whose orange bodies are silicon-based and 8′ tall on average, with thick, virtually impenetrable stone-like hides. First seen (as the Stone Men from Saturn) in Journey into Mystery #83 (Aug 1962).

Krylorians — A semi-humanoid race from the planet Krylor, third from the sun in the Aceta star system in the Andromeda galaxy. Krylorians have an extremely high level of technology, with advanced interstellar ships powered and guided psionically. They are also advanced in molecular-scale manipulation, transmutation, and robotics. First seen in Incredible Hulk #269 (Mar 1982).

Kt’kn — A semi-insectoid race with 2″ sperhical bodies with six spindly legs. They come from the planet Kn’kn, first from the sun in the Tk’kn star system in the Milky Way galaxy. They can communicate telepathically and have psionic senses rather than physical ones. First seen in Astonishing Tales #2 (Oct 1970). “Insectoid Disease”?

Kymellians — A humanoid equine race, who oppose the Zn’rx (”Snarks”). Kofi Whiteman, empowerer of the Power Pack, is a Kymellian. First seen in Power Pack #1 (Aug 1984).

The “K” could also be for “Keratinization.” Keratinizing Infection Derived from H*** ?

Or so I would write in if Marvel gave No-Prizes any longer…