Things from the Dungeon Dimensions - They are born of nightmares, and make nightmares, and are just generally nightmarish in general. They are not large ugly furry things; those are just bogeymen, and are generally much prettier. They are not demons either, as they do not rely on belief to exist. And the pretty ones look like a cross between an ugly octopus and an angry bicycle.
They crave life in a stable reality, so they try to break through into more ordinary dimensions such as the Discworld (it says something when the Discworld has a much more stable reality than the Dungeon Dimensions have). Magic weakens the boundaries between worlds, so the Creatures of the Dungeon Dimensions gather where there is a large amount of magic, waiting to break through. They also sometimes manage to come into the mind of a wizard, and these Creatures have an affinity to the number that is four-plus-four, so wizards try not to say that number (see The Discworld Companion).
Trolls - made of stone, become less intelligent in the heat. Ruled by a near-legendary diamond troll referred to as Mr Shine, who does not suffer from heat-intelligence loss. Have diamond teeth.
Dwarves - short, beards for both sexes, miners, expert craftsmen, very serious. "King" refers to a chief engineer, except in the case of the Low King in Uberwald.
Elves - transdimensional parasites who are experts in illusion. Capricious and violent, they take pleasure in taunting their prey. Iron has a negative impact on their powers. Divided between a King and a Queen. Often appear beautiful, but this is a consequence of their illusionary powers.
Banshees - Pale thin humanoids with leathery wings that look like a cape. Exceptionally strong, fingers more like talons. Civilized banshees wail at a death because it is expected of them. A wild banshees wail means death however because it is going to kill you. Possibly more common in Uberwald and Lipwig.
Vampires - undead, require blood to live. Not necessarily violent, many suffer from a highly advanced form of OCD, which allows would be vampire hunters to defeat them by throwing a bunch of seeds at their feet. This OCD usually manifests itself in something other than hunting humanoids in non-violent vampires. Usually strong, capable of flight, susceptible to garlic, holy water, holy symbols, attractive young women dressed in exceedingly skimpy nighties and developing long and esoteric sounding names to pass the time. If reduced to dust, a drop of blood on the ashes can restore a vampire. They are effectively immortal.
Ambiguous Puzuma - This leopard-sized big cat is the fastest animal on the Disc : it achieves near light-speed, given the low speed of light. This means that it cannot be proven to exist at any given time. Quantum anxiety, therefor, is a leading cause of mortality, along with ankle injuries from chasing females who aren't there. While it can never be seen, due to its extreme velocity, remains are found, occasionally, on the sides of cliffs and large rocks. These show a black-and-white checked coat and a thin, flat shape.
Basilisk - A rare creature found in the deserts of Klatch. Twenty-feet long with acidic venom. Its famous stare is rumoured to turn people to stone; while this is not true it will do the same thing to the mind as a blender would do to a tomato.
.303 Bookworm - A small creature that has evolved in the highly magically charged environment of the Unseen University. Because magical books are often dangerous, the .303 bookworm has evolved to eat books at incredibly high speeds. It can often be found shooting out of books, ricocheting off the opposite wall. This presumes that unlike other maggots, it has an incredibly hard carapace, as a normal pupated lifeform at those speeds would just go "splat", which means it misses out on the next stage of its personal development (the chrysalis followed by the mature insect). In fact, going "splat" at the worm stage would mean the species dies out, as only the mature adult may breed the next generation of .303 bookworms... so there must be some sort of hard resilient carapace enabling the creature to survive the richochet. By extension, a direct hit on anyone standing in the way would be fatal?). This makes it the fastest animal on the Disc (saving only the Ambiguous Puzuma– unfortunately, a race would be hard to arrange and impossible to judge, due to quantum uncertainty.)
Drop Bear - The drop bear is a predatory distant family member of the Koala which drops from a tree onto its prey. As a result the species has developed well padded backsides to cope with the drop. It lives in XXXX, although many doubt they exist at all. Rincewind was pretty sure he was attacked by them in The Last Continent. The drop-bear, or at least one of them, learnt a fairly important evolutionary lesson: never drop bottom-first onto any target, however tempting, which is wearing a sturdy and rigid pointy hat on its head. Whether it is capable of having any descendants to pass this lesson on to is a different story.
Megapode - A strange, rare, and retiring mythological beast which apparently is only seen in Unseen University once every hundred years. It is apparently a man-high flightless bird and coloured scarlet and yellow. It is not, in the opinion of Smeems the Candle Knave, the Egregious Professor of Cruel and Unusual Geography in a silly costume. Once seen, it must be hunted, with cries of "Ho, the Megapode!"
Quantum weather butterflies - These butterflies (Papilio tempestae) have wings of an undistinguished yellow with black mandelbrot patterns, and fractal edges of infinite length. A quantum weather butterfly can "create weather" merely by flapping its wings. It is possible that this is a sexual characteristic, that a male quantum weather butterfly will flap its wings and create, perhaps, a freak gale a few miles off, to show off its powers so to court a female quantum weather butterfly. Also, a quantum weather butterfly can make a small thunderstorm over, for example, the head of a bird that is trying to eat this butterfly, so the butterfly can flee the place and the bird might remember not to pursue such butterflies another time.
According to Vetinari in Feet of Clay, "the bodily fluids of the caterpillar of the Quantum Weather Butterfly will render a man quite, quite helpless."
Salamander - A lizard species that has evolved to live on magic. Salamanders look like lizards without a mouth. They live in deserts and sun themselves, absorbing all wavelengths in the Discworld sunlight. The salamanders use the octarine wavelength for their own energy and nutrients, and excrete the rest of the sunlight in much the same way that other animals excrete undigested matters. This excretion also happens when a salamander is surprised. Iconographers exploit this characteristic by keeping salamanders in a cage and using them as flashbulbs. In this capacity, salamanders have some roles in The Colour of Magic, Moving Pictures, The Truth, and most other occasions involving the use of iconography or the work of a newspaper.
Shadowing Lemma - A curious creature that exists in only two dimensions, and eats mathematicians.
Terrible Man-Eating Sloth of Clup - not much is known about this, except it is The Guardian of the giant ruby of the Mad Snake God.
Troll ducks - Nobody knows why evolution brought this species into being, as a silicon-based wildfowl is too heavy to either fly or swim. It is thought that they sink to the bottom and walk accross underground lakes.
However, the lake of pure mercury (re)-discovered by Rincewind in Interesting Times opens up a tantalising possibility. What if this is not an artificial construct, but a natural feature utilized by One Sun Mirror for his own ends?
If such liquid lakes exist naturally on the Disc, then an extremely dense medium which will neither poison a troll duck nor permit it to sink would be the natural breeding ground for the species...
Yeti - A sort of high-altitude troll adapted to living on very high mountains. Spins a thick fleece of extruded silicon fibres for warmth and bulk. First encountered in Moving Pictures when the distantly-heard Big Eats turn out to be a thousand indigestible elephants. On skis and sleds.
In Thief of Time we discover the species has an ability to manipulate time, so presumably the two specimens encountered in Moving Pictures learnt from what would otherwise have been a terminal encounter with a thousand elephants on bobsleighs - presumably they were able to pause and rewind, to a point where they could decide to be in a place where a thousand elephants on bobsleighs weren't. The Yeti's time manipulation is quite similar to the "save game" feature of video games on Earth. The Yeti is able to save its time at a certain point, and then venture forth knowing that if it dies, it can just resume its life from the point it saved at with the knowledge it acquired before death. It is effectively a highly evolved, albeit slightly painful form of foretelling. It is possible- as demonstrated by Lu-Tze- to learn how to do this without evolving it naturally, but given the difficulty involved in this method of survival when it isn't built in the person attempting it would have to be truly desperate to attempt such an action.
They are hunted for their feet, which as everyone knows have aphrodisiac qualities, as big feet mean other extremities are also oversized. Well-known fact, that is.
