Lurker Above: This monster, sort of like a manta ray that clings to the roof of a dungeon and drops on the heads of adventurers, first appeared in The Strategic Review #3. Gary must have been very happy with this one, because the only change to it is that it is now better at gaining surprise.
Lycanthropes: Lycanthropes first appeared in OD&D Vol. 2, and were expanded on in Supplement II. Most of that expansion has been discarded in favour of some new guidelines on how lycanthropy is passed on. The disease, previously able to be passed on to any warm-blooded creature, is now restricted to humanoids. There’s no longer a rule about the disease being more potent during the spring. Supplement II had some complex rules to determine when a lycanthrope’s animal persona takes over, but that’s been simplified to a 90% chance during the full moon. The rules for family packs have pretty much disappeared, only being present in the entry for werewolves. Belladonna now has a purpose, as characters can use it to try and cure themselves, with the risk of dying from the poison. Any infected character could previously be cured by a cure disease spell, but now the caster must be 12th level, and instead of having a window of 2-24 days to be cured, you now have a mere 3 days.
Werebear: Werebears have had a drastic drop in their Number Appearing (from 2-20 down to 1-4) and a slight increase in Hit Dice (from 6 to 7+3). They now have a number of new special abilities in addition to their previous bearhug attack. They can summon brown bears, which is actually drawn from the Chainmail rules. They heal three times faster than normal, are immune to disease, and can cure any other creature of disease over the course of 1-4 weeks.
Wereboar: Wereboars have had a similar change in Number Appearing (from 2-20 to 2-8) and a Hit Dice increase (from 4+1 to 5+2). Otherwise, they’re the same as ever.
Wererat: These guys first appeared in Supplement I. Their Number Appearing has been reduced from 8-32 to 4-24. Their Armor Class has changed from 7 to 6, and their Hit Dice from 3 to 3+1. They’ve now lost their bite attack, and rely solely on weapons in combat. In OD&D they had two forms, human and big rat, but now they have three: human, ratman, and giant rat. They gain surprise more easily now. They’re also said to live in tunnels under cities for the first time. Wererats in the sewers is a very common trope for this monster, but this is the first time it's spelled out. Is it from the Fritz Lieber stories? I have to get off my arse and read those.
Weretiger: Their Number Appearing has changed from 2-20 to 1-6. Their Hit Dice has increased from 5 to 6+3. Their bite attack is better, now doing 1-12 instead of 1-10. They now have the ability to converse with all types of cats (although they prefer not to mingle with them), and they can rake with their rear claws to get some extra damage. It’s also said that they’re most often female.
Werewolf: Their Number Appearing is almost the same, changing from 2-20 to 3-18. They also gain three extra hit points. They’re the only type of lycanthrope that is said to travel in a pack, and they use rules similar to the family pack rules from OD&D; if the female is attacked, the male gets bonuses to attack, and the female gets bonuses if its young are attacked. They’re not the same rules as before, but the intent is the same.
Giant Lynx: The giant lynx first appeared in the wilderness encounter tables from Supplement III. This is the first time it gets stats. They live in cold regions, are very good at hiding, gain surprise often, and can detect traps. Their most important feature is their intelligence: they are listed as being Very Intelligent, which is better than the average human. This makes them much more interesting than the average animal encounter; certainly there’s nothing about them that’s statistically interesting.