DMR2 Creature Catalog - W, X, Y: Water Weird to Yowler, and that's the lot.

Water Weird. 

Basically the same as the AD&D MM Water Weird. Some slight statistical difference.

As seems fairly common between AD&D and D&D (as the dividing line existed previously), the CC's Water Weird has 2 Intelligence vs. the MM's Very (11-12). 

CC's also lacks the ability to take control of Water Elementals, so maybe that's tied to Intelligence, but the idea of Water Weirds as elemental tape worms is quite appealing. 

Whipweed.

I think this is the only monster to have crossed to CC from the 1e Fiend Folio, having first appeared in a pre-Fiend Factory (?) issue of White Dwarf. 

It's a plant that lashes and grabs you with its two fronds, then secretes acid on you until you're dead or escape.

It's not a monster I've given much thought about until looking at them now, and I prefer the FF's overall portrayal: it's a creature that was previously mistaken for a plant (but is affected by Druidic plant-magic, implying not that of Clerics and MUs), and if you sever the fronds/tentacles, the lumpy little body attempts to escape on root-like legs.

Retrospectively, it's a bit like a bit of John Carpenter's The Thing, so two thumbs up for that.

White-Fang.

Distantly related to white dragons, this is otherwise your standard fantasy cold-dwelling furred serpent -  which is a monster type I generally like, on top of it being something that could be mistaken for a dragon in a setting without Dragons.

Tim Sell, he illustrated House of Hell.

It's got magical venom that freezes your blood: paralysed and lose d8 hp per round until you die or you're rescued, all the while turning blue. Even if you save, it leaves you numb and cold, with Strength and Dexterity penalties.

Also has improved infravision that can see heat hidden by cold (snow, ice, water, arctic atmosphere). They themselves are 80% undetectable to your infravision.

That the venom is magical suggests that dispel magic should work as well as neutralise poison, but that's not stated in the text, nor acknowledged in 2e.

Winged Warrior.

A Living Crystal Statue with metallic bladed wing-extensions on its arms. Though it is under a permanent fly spell, it apparently needs its wings to fly as it must land to fight.

Apart from the ability to fly it's not mechanically different to the Living Crystal Statue, not even getting better attacks with those razor-wings.

I'm going to guess that they cropped up in a module and were hoovered up into the CC without discrimination. The relative simplicity of upgrading a regular Living Statue to a flying one implies that there could be equivalents for all varieties (except maybe Jade, due to magic resistance).

Wood Imp.

No relation to the AD&D Imp, they're basically faerie/forest goblins, and I have a place for such as these.

Traps, camouflage, ambush/surprise, ride on the backs of (Huge Wood) Spiders, poison arrows (damage and slow). Their two-handed swords score d6, so maybe they could handle a short sword. Shamans up to 4th level (Cleric).

They capture evil humanoids and humans [and] small forest creatures, but it's not made clear if these constitute a larder, sacrifices, slaves or prisoners for ransom.

Tall Tales of the Wee Folk gives more context and makes them playable characters. I imagine they look more like Pathfinder Goblins than D&D.

2e gives us the Bog and Garden varieties. Bog (slightly froggy, make a cry akin to that of a puppy) and Wood Imps are not that different, and not that different from something like the Tasloi in any case. Garden Imps (with flowers growing in their hair) seem closer to something like the Brownie, as they watch over any dwelling attached to its garden.

Wychglow.

At first glance, this seems to be the BECMI/Mystaran analogue of the AD&D Will-o-(the)-Wisp, by form and by electrical attack (although it has significantly weaker AC and HD). 

It was meant to be in the Companion set (1984), but the Prime Plane monster list ends with Whales.

However, rather than feeding on life force, it feeds on the electrochemical energy of metal objects. As the process can take hours or even days, it kills you first to get at them, eventually reducing the metal to a fine, chalky dust. Your Fighters and your Clerics will be their primary targets; Thieves and Magic Users can save for no damage, with a +5 bonus due to leather or no armour.

You could read that it doesn't feed on or will be distracted by precious metals, as the text specifies it goes for plate armour, shields and weapons for preference. It seems that size is more important than quantity, so maybe leading it to that golden statue (or Silver Golem) will save your bacon.

One thing that does cross-over from the MM is the (Exceptional) Intelligence: the Wychglow has a score of 15. Which seems quite high for something that does not otherwise suggest or specify an intellectual bent. 

Is this more a Star Trek energy being alien than a haunter of the lonely marches? Probably. There's obvious room for negotiation if you can find a way to communicate with it, especially if you don't cleave too close to Chaotic=bad.

Wychlamp.

Weird little extra-planar energy beings with a folkloric name. My memory had them as being related to Wychglows (above), but it's just that Wych is a strong word.

They're attracted to, disrupt and immune to magic, but are basically non-aggressive. They might accidentally discharge energy into you (2-5 hp and slow). The text suggests capturing one or more in a net to use when trying to slay spell-casters.

Wyrd.

An undead spirit inhabiting the body of an elf - so a bit like the Undead Dragon, these might not actually be the undead version of a particular live thing, and maybe there should be details on that disincarnate entity/

Greater and Normal Wyrds look like creepy, robed, undead Elves, wielding green or red spheres that they can use as both melee and missile weapons. These cause more damage vs. live Elves, and are instantly replenished if expended.

Terry Dykstra for The Bane of Elfwood in Dungeon 21.

Greater Wyrds trigger a fear save vs. attack and damage penalties, as well as causing paralysis via their spheres.

Because of proximity and Wy-, I can't help feeling these should be somehow connected with the previous two monsters - maybe even wielding them as alternatives to their usual spheres? 

2e connects them to the Positive Energy Plane.

They're in a pretty interesting (to read; never got to play) adventure in Dungeon magazine (see illo), which includes a possessed treehouse.

Xytar.

Six-legged, fire-breathing, brightly-coloured dragon-lizards. Preferred companion animals of the Sis'thik.

Extrapolating from their six-leggedness, they could be related to Basilisks via the Elemental Plane of Fire (give them the Pyrolisk gaze attack for consistency). In which case, maybe Black Dragons (or some other type) can produce viable offspring with them, or maybe Xytars are Red Dragon Dracolisks?

Yowler. 

Yowlers are Yeth Hounds, with the same stats and abilities, though the Yowler's howl incurs a penalty to the save the more Yowlers are yowling, which is both a good detail and logical.

A decent Black Dog monster, also suitable for inclusion in your Wild Hunt.

Pointlessly brought into 2e instead of just updating the Yeth Hound entry, either with the howl details or just saying 'another name for them is Yowlers'. 

Conclusion.

...which makes them something of an anti-climax; there's not even a new type of Zombie to take away the somewhat disappointing taste (Zombie, Lightning in the 2e Mystara supplement).

By an almost-uncontrived coincidence, I'm just about to reach the Yeth Hound episode of Monster Man.

So the end of Monster Manual II, and then the next season delves into the Creature Catalogue (AC9).

Now I'm aware of Monster Man and that it's covered/covering the same ground I have, there's diminishing returns in me looking to the better known old school D&D-ish bestiaries. So I doubt there'll be a Fiend Folio read-through, but there might be ones for White Dwarf Fiend Factory mini-modules and so on. We'll see.