Kamaitachi: a wolf-sized weasel with long sickle-like claws that dwells in the Northwall mountains, and employs a limited form of Wind magic.
Kameleon Kong: A 20' white gorilla with the ability to blend into its environment with near perfection. Not true invisibility, and apparently not usable in combat, but this talent does allow for frighteningly effective ambushes. Territorial in nature, Kongs do not get along well with people.
Kappa: an amphibious breed of common troll found in the Yamato region. The folktales saying that they need to keep the depression on the top of their head filled with water or they will die is not factually accurate: they just need it to enable their unique form of water magics. The stories about their love of cucumbers are entirely true, which is why they appear to universally despise chocobos.
Karkinos: There are legends dating back to the Divine Era about a war between the great powers of the day and demonkind. Karkinos are weapons left over from that time. Bronze golem crabs thirty feet across (not counting the legs!), with three scorpion tails. Each tail can fire an elemental Light attack, at separate targets. There are several known to be roaming the deserts of the North and South continents, and every few generations, someone digs another one up. Not hostile unless attacked, but no one knows how to control them.
Karma Dog: A black furred canine the size of a lion with short goat horns, feathered wings, and a spiked mass on the end of it's tail. Damage from one reduces one's luck, and the effect accumulates. Tales say that they are created from the death-curses of the innocent.
Kasit: A nightmare creature known to torment subterranean communities and underdark-adjacent surface villages. A Kasit hunts by assuming the form of someone its victim trusts implicitly, then closing in for the kill. It is unknown if the monster changes shape, employs illusions, or depends on mind magic: very few specimens arrive sufficiently intact for the arcanologists to study. A kasit's true form resembles Gollum, with less hair and a sucker mouth. These creatures usually kill by strangulation.
Kitsune, Greater: mythical fox beings who can take the form of beautiful people, foxes, or warg-sized monsters. Descended from the gods of Fire and Mischief, they amuse themselves by making mortal lives more exciting. In their favor, they despise Youkai.
Kitsune. Lesser: resembles a wolf-sized fox with a significant elemental Fire aspect. Not sentient, but possessed of high animal cunning. The greater number of tails on a kitsune, so increases the number and power of fireballs it can hurl at its enemies. True kitsune cannot be domesticated, a rarely understood fact as this is a popular form for elemental spirit familiars to take.
Kobayashi: Fundamentaly, a merchant wagon mimic. Usually a two-wheeled cart pulled by a pair of chocobos, plodding along the back roads. When approached by foolish bandits, nosy guardsmen, or curious peasants, it will transform into a two-headed drake. A very fast two-headed drake. Older kobayashis will mimic four-wheeled, horse-drawn wagons, and are usually smart enough to sign on with canny merchant groups.