Jaguarmundi: Not to be mistaken for a jaguarundi. A human-sized spotted feline predator with great cunning and an intense hatred of people. Jaguarmundi are excruciatingly difficult to kill, as they are not only immune to all forms of magic, but can actively neutralize ALL exotic abilities over an area of about an acre. The most common method for hunting one is to drive the jaguarmundi with fire into the open, and snipe it with a master archer or arbalesteer from a quarter mile away.
Jhun: A form of undead found in the coastal and marshy areas of the Hazad Caliphate. Toad-like in form, with a long tongue and a droopy, tapir-like snout, most jhun are about twice the size of an ox. Jhun grow by swallowing and integrating the corpses of their victims: once defeated, the beast can be taken apart to reveal the bones and haphazard organs of scores of creatures within. They spend the day underwater, and only hunt at night: as undead, sunlight damages them.
Joanna: Considered clear evidence that an elemental plane of Necromancy is forming out there somewhere. Pack hunting monitor lizards whose physical attacks also directly drain life energy. They are also fast, project a fear aura, and the pack leader can talk. No one is certain where they come from “naturally”, but there are several dark rituals in circulation if you really want a set of your own.
Jön-jön: A nightmare creature with origins in the Elven Principalities, though of course they have spread to other regions. Appears as a shadowy humanoid figure on the road ahead of you at night. If chased, it will flee, keeping its distance. The problem is that a Jön-jön exists in two places at once, and while you're chasing one, the other part is sneaking up behind you to stab you in the back.
Jumping Jakin: A humanoid plant monster with a spindly body mostly comprised of vines, and a jack-o-lantern for a head. Jackin are famed for their mobility, their rich flavor, and their unfortunate tendency to end up in the service of sentient undead.
Jumping JaKing: A thirty-plus foot tall sentient Jakin with a powerful affinity for fire, necromantic, and plant magic. The appearance of a JaKing usually spells the end of the undead that had until then been ruling the jakin patch. And for any nearby villages.