These are several entries I contributed for a bestiary in the Tamriel Rebuilt mod. It's a communal effort, so you'll have to play the mod if you want to read the mall.
The Slaughterfish
This carnivorous and aggressive creature can be found in lakes, rivers, and along shorelines across Tamriel. They are considered a curse and a pest by all who venture on the water, though their scales are prized by alchemists, and, in certain reaches of Argonia, used as currency. Among sailors the story goes that slaughterfish are the souls of those who betray or kill a crew member, set about by Molag Bal to hunt their former comrades. Thus large groups of slaughterfish can often be seen trailing ships for miles in the open ocean, and slaughterfish are known to occur in far greater number the closer one gets to the fabled Maelstrom of Bal.
The Snow Whale
Much is written in Nordic lore of the snow whales, majestic beings who live among the highest mountain peaks, and freely move through air, snow and ice as if swimming through water. Children's stories portray snow whales as the singers of clouds, and claim that their emanations are the cause of all the joy in the world. This is why Nords and children alike grow cheerful in the snow, and celebrate the cold weather even as it obstructs their paths and endangers their crops.
The Troll
A large, ape-like monster, prone to lurking in caves and forests across Tamriel. Western breeds are distinguished by a remarkable third eye on the forehead. Trolls have the ability to recover from any wound, and, unless scorched by fire, can even return from death in this way. This has led the Order of Arkay and many Meridian cults to declare the troll a revenant beast, to be exterminated under their various divine pacts. Trollbone is a popular material for armor among the Nords, who believe that the regenerative capacity of the trolls will keep their armor maintained, and may even be transferred upon the user in the hour of need. They are not alone in this supposition: trollbone charms and amulets can be found among the Reachmen, the Bjoulsae tribes and various Bosmer clans. Furthermore, powdered trollbone is a popular ingredient in Nibenese rejuvenation potions, and the extinct Kothringi nomads were said to hammer sharp splinters of trollbone under their skins in times of war.
The Petty Troll
A diminutive cousin of the western troll, these small three-eyed monkeys can be encountered in southern Pellitine and along the Niben river valley. Originally forest dwellers, these creatures have in recent times moved into the cities, where they are regarded as a pest the likes of rats or street dogs. Packs of petty trolls have been known to rob market stands, attack passersby and, though not carnivorous, they have developed a sinister reputation for cradle-robbing. In the Nibenese totem-worship, the petty troll is considered a minor animal spirit, protector of inexperienced thieves and the more vulgar sort of bandits.
The Carnelian or Imperial Sea-Snail
These massive snails can be encountered in the mangroves of the lower Niben delta, and are easily recognized by the great, horned shell they carry around on their back, which serves them as a home. Among the Nibenese, they are much prized for the vibrant red dye they secrete, which is said to be an exact imitation of the Imperial ruby's color. As such, all official banners and heraldry of the Empire must be painted in sea-snail red, and many villages are dedicated to producing this dye. In the wild these snails rarely grow larger than a man, but in captivity they can grow almost unlimited, and it is not unusual to see their shells used as houses along the east banks of the Niben. Tradition dictates that, once every five years, the Emperor must sail down the Niben and exhibit the Amulet of Kings to the gathered sea-snails, in order to remind them of the color they are to produce.