Jackal: Jackals had first appeared in Supplement I, as one of the animals that can be summoned using a bag of tricks. Of the few stats that had been previously established, only Armor Class is changed (from 8 to 7). They’re quite weak, and said to be cowardly and not particularly fierce. The text outright states that they’re only here because of the bag of tricks. Gary actually sounds a little bit apologetic.
Jackalwere: This is a new monster. The jackalwere is a sort of reverse lycanthrope – rather than being a man that can take the shape of a jackal, it is a jackal that can take the shape of a man. Their main attack is a gaze that causes sleep, and they can only be struck by iron or magical weapons. Described as malign foes of humankind, they pretty much exist to kill people, eat them, and steal their treasure (not unlike most adventurers).
I feel like I should be able to make something of the reverse-lycanthropic nature of these creatures. Certainly they must tie to the other lycanthropes somehow. I’m leaning towards jackalweres being the more ancient of the two – it just feels right. I’d like to connect them to the origins of lycanthropy, if at all possible, but that’s some thinking I’ll leave to a later date.
Jaguar: Jaguars first appeared on the wilderness encounter tables in Supplement III, but they get stats here for the first time. They’re hard to surprise, and if both of their claw attacks hit, they can make extra attacks with their rear claws. Any monster with five attacks a round isn’t to be trifled with. I’m a little dubious about their ability to leap 30 feet into combat, but admittedly I know very little about these animals, and I gather that Gary used to enjoy watching wildlife documentaries. So I guess he knows what he’s on about.