Cockatrice

Due to etymological brain mush, I resisted the urge to call these things Cockatrix(Singular) and Cockatrices(plural) and instead settled on Cockatrice(Singular and Plural) for no good reason at all
AD&D Cockatrice
Cockatrice turn people to stone via touch, and come in small groups of 1d6. One thing you probably wouldn't expect from a chicken sized monster is that it has 5hd and a low AC, making it a sort of HP sponge that will give it plenty of opportunities to force saves vs stone. Like the Basilisk, its petrification aura 'extends into both the astral and ethereal planes' making it a menace to things like ghosts and, I suppose, githyanki space pirates. One must assume that touch-based petrification is not prevented by armor or clothing, explaining the high hit chance of a 5hd creature.

3.5 Cockatrice
Pretty much the same, but instead of multidimensional petrification, they have immunity to other cockatrice petrifications, presumably so they can breed.

Mythic Cockatrice
 Displaying overlap with Basilisks, some cockatrice had killing gazes to be reflected by mirrors. Or dealt with with weasels, who were immune. Some had killing breath, or a vulnerability to a rooster crowing. As with many D&Disms, petrification is a softening of the death-bringers of mythology.
They are also said to be descended from an egg laid by a rooster and incubated by a toad or snake (vice versa results in a Colo Colo).

Nethack Cockatrice
These turn you to stone with a touch even after death, making them dangerous hazards. They also can turn you to stone if you hear them hiss, though this can be prevented by eating a lizard.

Sunset Realm Cockatrice
Yg, Mother of Serpents, Longest Librarian, etc etc, is responsible for many petrification effects, or at least the ones that rely on a memetic infohazard to induce a liminal stasis loop between comprehension and ignorance (further explanation requires continuation in the Serpentine language, not clumsy Commonid).

thousands of years of magical weaponsmithing will probably never compare to a cursed chicken on a stick

Cockatrice are no exception, though Yg is only indirectly responsible in this case. A rooster is taught how to lay an egg (typically via dream-quests orchestrated by a snake-person) and the egg is then blessed by Yg in a religious ritual, and bada-bing-bada-boom, you've hijacked the biology of birds to create a weaponized conduit of Yg's infinite wisdom. While basilisks were guard beasts, cockatrice are nonlethal bioweapons designed to clear out problem areas of pesky guerilla(and gorilla) rebels with support from snake-people (snake hearing is different, on account of their lack of ears and so on, and they are immune to cockatrice hissing). Rebels who avoided the slow-onset petrifying hiss could be poked with the cockatrice directly for immediate pacification. Cockatrice leashes (mistakenly ID'd thousands of years later as 'Pike-Flails') were long poles with short chains at the end which allowed some freedom of movement, but not enough for wielder and cockatrice to interact physically, and also allowed for the cockatrice to be wielded like a rubber chicken on a stick.

As the contact petrification occurs due to fractal feathers encoded with infohazards communicating via the feeling of the fractal feathers, thick gloves, armor, or even nerve damage are sufficient protection against the touch of a cockatrice, but fresh, undamaged cockatrice corpses retain their power. Individual feathers are not sufficient, and rearranging the feathers unduly likewise alters the infohazard to uselessness, so the only option for wielding cockatrice as melee weapons really is to use the whole thing.

Cockatrice are ornery but not physically dangerous- they are snakey chickens is all. While fairly agile, one good hit should slay them, and apart from a minor possibility of losing an eye to a peck, petrification will ensue before anyone succumbs to chicken beak and talon. Weasels are immune to petrifaction due to rival Alvish bioengineering and will slay Cockatrice where they are found, and the crow of a rooster at dawn kills cockatrice instantly.

The Hiss- If you hear it clearly (within 30 feet or so) save vs stoning or pick a limb to turn to stone. An additional limb turns to stone every round/~10seconds. Snakes and weasels immune.
The Touch- Feeling a cockatrice's feathers on bare flesh (or through thin clothing, perhaps) causes a save vs instantaneous petrification, as does a successful melee attack from the beast.
Unlike basilisks, which require their own saliva to depetrify their victim, any snake, reptile, or frog venom will suffice to undo the touch of a cockatrice, as any old snake foot(or lack thereof) soldier needed to be able to destone prisoners.

The Toad Thing
The upstart Toads were able to come up with cockatrice of their own(as well as many other monstrosities), being well versed in the powers of change and metamorphosis. This didn't save them from the Snake Empire, but it explains why the froggy folk of the Dismal Bog (the moonland area of the Bog of the Canal) are so keenly aware of the dangers of cockatrice, for ancient lineages of the beasts (some said to have grown to tremendous sizes) are known to lurk in forgotten temples.

soggy, concealing cloaks and bandages to keep their skin moist are the outfit of the frog-ilk who venture into drier lands

,

Centipede, Cerebral Parasite, Chimera

OG Giant Centipedes
Giant Centipedes are the classic 'low level vermin introducing save or die poison.' They have a mere 1/4th of a HD, meaning 1-2 hp, and don't even deal damage, just save vs poison at +4 or die. While modern osr games often have death and dismemberment at 0hp rather than a flat 'you died,' if you were playing with random 1st level HP and immediate death at 0, centipede death venom is statistically safer than anything that deals HP damage of a damage die greater than your own HD.

Sunset Realm Centipedes



In ancient days of the 4th sun, the great goddess M'shesh, Mother of Undeath, had been driven from the waking world. Her temples were fallen or forgotten, her living cultists were slain, and her dead cultists were sliding into madness. She strode through the gloom of the spirit realm on the edge of Nightmare, far from the light of the outer or inner heavens, a thousand thousand of her followers following her tattered skirt. For every step she took, another soul was sent to her, screaming with the memory of being burnt by the light of the Tyrant Sun Riikhus, and another soul was lost to her, fading into the gloom, taken by some unknown temptation of the grey netherworld, perhaps to return someday, and perhaps not.

Before her was a deep swamp named Despair, and though her titan bones could wade through the murk, she feared for her tiny faithful. It was then that she came across a small heaven, dreamt by a mother centipede with a hundred children held in a hundred arms.
"I envy you, Centipede, for you can hold all that you cherish." M'shesh spoke, a hurricane.
The centipede waggled her antennae knowingly. "So too can you, Black Wind."
M'shesh looked at her arm-bones, each as vast as the mast of a ship built by giants. "I have but two limbs for this purpose, Hundred-Legs, but a thousand thousand children, and a thousand thousand more beings I wish to protect e'en tho I am spurned by they."
"She-Who-Bars-The-Way, this small one cannot help but notice you have a hollow skull, and broad shoulders, and spacious ribs, and a many-tiered spine, and wide hips, all which bear only sighs and echoes at the moment." So spake the little insect.
And then M'shesh was wiser than before, and she gathered up all her followers to her bones, and forded the swamp called Despair without a single drop of mud reaching her children. So it was that the faithful of M'shesh found their afterlife, the Osseous Scaffold, where they hang from the bones of the goddess awaiting rebirth.

All predators that care for their children are object lessons of how the sacred impulse to protect life can coexist with the profane impulse to hunt and kill to survive.  Centipede iconography is the favored symbol of this in modern M'shesh temples (ancient temples tend to show large mammalian predators). Heretic undead (such as vampires) that create spawn by forcing undeath upon others are sometimes branded with centipede tattoos, or bound in centipede-themed manacles.

OG Cerebral Parasites
Cerebral parasites are another stupid gotcha monster built to counteract psionics in such a way that it seems blatantly clear somebody involved with the AD&D MM really disliked psionics in their game. They're invisible, removable via Cure Disease, attack and are  unnoticed when doing so, and each one will drain psionic points whenever psionic powers are used and reproduce every 6 points drained. So basically you get invisible lice, lose your psychic powers and aren't sure why unless you have someone 'carefully inspect your psionic aura.' At least diseases and rot grubs have a bit of an advantage in stopping money-grubbing players from searching through trash constantly. (If you're wondering why that's a problem, consider that continual trash-sorting is a waste of game time that could be used seeking out actual treasures in actually interesting areas. But if your players all agree that trash-shuffling is great, you probably need to give them a treasure map rather than give them rot grubs.)

There are none in the Sunset Realms.

fixed it now tho

OG Chimera
 I was never a fan, really. 3 different AC's given with no explanation given, a full half-dozen relatively weak attacks simulating every single pointy end of the beast, and a 50% chance of firebreath. Also a number appearing of 1d4, another departure from the idea of the creature as a lonesome abomination. Not to mention Treasure type F which promises great treasures but usually delivers a single underwhelming result.

They just seem like a weird monster only good for the appearance of variety, while basically just being a nerfed dragon. Nothing really stands out beyond 'Hey you know that Greek Myth you read? Well here's a physical representation of that, stripped of the meaning and context of the original! Now hit it with a sword!"

And for whatever reason, I have it in my mind that a proper chimera has the head of a lion and a goat in front, and a serpent for a tail. D&D insists on a dragon instead of a serpent, and all three heads up front, and so that's all I have to say about that.

Sunset Realm Chimera
Though the classic goat-lion-snake-wing combo is well known due to a widely popularized but slightly misunderstood Beast Battle championship duel, the term 'Chimera' has both common parlance meaning any old mishmash of beasts, and an 'Official' definition which requires wings, 3 heads, at least 4 source animals(none of which may be humanish) and an unnatural origin. Chimera are not sterile, but as any potential mate must appeal to all heads of the beast, it is dashedly hard to establish breeding stock.

In any case, most chimera are not noble combinations of impressive creatures, but mishmashes of domestic animals created by mad alchemy for Beast Battler tournaments. Though there is no limit on creature combination, there are several common combinations that have gained popularity.

Rabamirel- A combination of rat, bat, mole , and squirrel. Cute and cuddly if you like rodents. Technically not a chimera, as they have only 2 heads.

Ultrabug- Spider, Scorpion, Centipede, Wasp. Terror/appeal/availability self explanatory.

Cagolope- A combination of cat, goose, and jackalope, these small but fiesty chimera are known for the wing placement which is commonly thought to be 'backwards' but when viewed as a quick backwards retreat option rather than a means of migration, the odd wing placement becomes intriguing in arena settings.

Crapmera-A combination of hyena, buzzard, worm, and pig(biting with the hyena head, charging with the boar tusks, flying with the buzzard wings, and waving about slimily with the worm-head tail) these middling-large-size creatures are considered filthy and unclean by a wide range of people, but are very easy to feed.

...And so on and so forth. If you wish to create a chimera of your own, the easiest method is to feed something a Potion of Fusion, throw it into a sack/cauldron with the things you want it fused with, and shake/stir vigorously- the animals willing to live on as part of an abomination will have heads, and those who depart the waking world will leave behind only wings, tails, claws, etc. Chimera created this way are notoriously foul-tempered.

The other method is similar to homunculous creation, in which the blood, eggs, spit, seed, etc of a creature (or creatures, in this case) is added to a sort of nutritious potion so as to create a rapidly maturing clone-thing that will have the disparate souls within satisfied with their body.

Since chimera add their mass together rather than averaging it out, adding in massive sea creatures can result in great success.

Centaurs

OG Centaurs

Centaurs from the AD&D MM feel mostly like 'Fairy Tale' centaurs- sylvan, friendly with elves and gnomes but not humans. Their roving encounters are armed as follows- half being clubbers, 25% being archers, and for the remaining 25% of leaders, light lancers. I suppose this weaponry is all of wooden construction.


As expected of old GG, Gygax notes that you have a 90% chance of being to ransom the women and children (stats for slaughtering them are provided for Anakin wannabes ofc) for the centaur's treasure types of D, I, & T, which is a pretty good haul all things considered- no wonder they don't trust humans and dwarves.


From this one might conclude that the lance-bearing 'leader-types' are the men who have families, explaining why centaur leadership is prone to valuing the women and children above petty trinkets and baubles. That further implies that bravery and combat skill is valued, as 'leader-types' have lances that require charging into battle, so some sort of martial patriarchy seems a likely form of governance. The clubbers are probably men hoping to distinguish themselves in battle with threats to the herd, while the archers might be the low men of the social ladder, as they cannot distinguish themselves in melee with a bow, and are developing a different skillset entirely and so would be unlikely to 'upgrade' to lancers even if they slay many enemies with their bow. I would guess that the task of bow-hunting is necessary but dishonorable, a job assigned to centaurs who are viewed as cowards or slow-hooved.



Sunset Realm Centaurs
When two souls love each other very much, they can create offspring. See below for details

I had some players sell their firstborn child to Alves for minions. As no firstborn were immediately forthcoming, it fell to said alfspawned minions to give the players 'the talk.' The minions were under the impression that the only reason the players weren't breeding immediately to fulfill the contract was due to a lack of understanding of the metaphysics involved in the creation of new souls.

One might wonder how species are even separate at this point, and the two leading theories are

1.  Vanity leads souls to prefer forms that match their own bodies, and speciation is primarily a matter of aesthetic preference.

2. Light is orderly and categorical, so lands lit by light have suns, moons, and gods maintaining reality, whereas in the dark, everything is basically the same. That's why sunlit beings and moonspawn can be sorted into categories, whereas darkspawn are basically just a chaotic mishmash of different things, all unique but also, all alike.


This means that freakish hybrids have a perfectly normal explanation, but it's rare for the will of such disparate souls to align in such a way in the wild. Most lions and hawks will have little contact, so they can't fall for each other, hence griffons are rare (though hybrids breed true with their own hybrids, meaning semi-stable populations can emerge.) Humans and domestic animals have considerably more contact with each other though, so...

Centaurs are what you get when a horse and a human get together, meaning they broadly emerge from lonely farms and noble knights. The former just tends towards sad stories of single parents and youths who never fit in, the latter leads towards scandals and succession crises requiring thrones to be moved into the stables, or vice versa.



Centaurs are most common in King's Point/Queen's Coast/Prince's Spit, where chivalry trumps common sense, mounted knights are common, and there are several established options for a centaur of noble lineage.

1. They can work to be so charming, diplomatically astute, and full of social grace that they can be accepted into high society as just another noble with a big butt hidden under a hundred pounds of lace dresses. This tends towards repression and self-loathing for ones horsey half, but the castle of the duchess Chira Loquacia, a centaur who won't be shamed and won't be silenced, is built to accommodate these folk and proclaim the validity of being half-horse(though the inevitable matchmaking with other centaurs from the incorrigible duchess may wear one's patience thin).

2. They can become natural-born cavalry knights, clad in armor and purging the land of revolting monsters and peasants. This can lead into #1, or the extermination of monsters for Our Lady of Gardens can earn them enough favor with that stuffy goddess to invoke a miracle. Our Lady of Gardens tends to be fond of the parts of the whole that is the offspring of a noble human and a thoroughbred horse, and centaur champions may be rewarded with transformation into a human, given the ability to change between forms (night and day, typically) or, more rarely, separated into the fraternal twin horse and human their twin-soulled body was 'meant' to have been born as.

3. They can flee to the nearby Wurderlands and find acceptance in Wurdton, where the Lord of Calamities, the deity Murulu, presides over all manner of folk deemed too monstrous of form to fit in elsewhere. This is, of course, a rejection of Our Lady of Gardens and the establishment of human society and is located in the perilous moonlands, so one must be well and truly fed up with society to take this option.


Bonus Notes on Centaur Physiology


Centaur knights would have their backs snapped if they charged upright holding a lance in their arms, so they either lean way, WAY, forward to take the shock of impact down their spine rather than perpendicular to it (more common with light lances and armor) or have lances mounted on heavy armor so that steel and horse-shoulder takes the hit. These armor-mounted lances are not so much wielded as they are swiveled into attack position

Centaurs can eat anything humans can, and things like hay that humans can't. However, their teeth aren't great for that, so if they're gonna eat hay and oats, they need to mill them into something more easily comestible. Typically it's easier to just eat high-calorie human food than to go whole horse.


Breastfeeding is difficult- baby centaurs are too heavy to be cradled and nursed to human breasts, but too tall to reach horse teats properly. Some combination of kneeling, stepladders, or just milk in a bucket is probably necessary until weaned. Speaking of breasts, shirtless female centaurs seem an unlikely fantasy to be supported unless they are very flat-chested indeed- if humans IRL prefer sports bras when exercising, the galloping and cantering and trotting and so on of a horse would surely be even more unpleasant.


Centaurs as beast of burden is seen as disrespectful(unless they're a peasant centaur in which case they were beasts of burden either way), but centaur knights can find it quite handy to have a squire riding on them to pass them new lances and so on. Typically a centaur-mounted person rides facing backwards, as the centaur needs no one to steer them, and can really appreciate someone watching their back and flank.