These creatures are native to the world, unlike demons and celestials. Yet they are still powerful and/or magical. Due to this power, they are featured in Imperial myths and legends. Yet they are all too real.
Corpsewalkers: The remains of a lizardman(mostly Steelskulls, but one or two other clans have reports as well), that were not properly disposed of. For steelskulls, this means cremation. They are enraged at this improper disposal, causing them to go on a murderous rampage. An unyeilding monster fueled by rage would be scary enough, but their souls are still within their dead bodies. This gives them all the skills and combat prowess they had in life. Every spell they knew, every weapon they used, it's all still in there. The only way to stop them is to release their souls and let them go to the gods. Burning the body is the most accepted way of destroying their fleshy prison.
Arcane Beasts: As the name implies, these are animals that have been infused with arcane power. Whole species are rarely infused to any degree. The best instance of a whole species being infused is the Manatwisters, but individuals can become infused fairly easily. This makes them smarter and, more dangerously, lets them cast arcane spells. This can be dangerous if a predator is infused, but any animal with magic can misuse that power. Some famous examples include
Bronzeclaw - a giant lobster who gained arcane defenses, making it a veritable tank. It was killed after attacking a large settlement of Mudclaws, and escaping back to its swamp lair.
Blinkstrider - A bloodbeak moa who was given the powers of increased speed and minor teleportation, allowing extreme hit and run tactics. It has not been killed yet, but has been driven deep into the plains, away from any Imperial settlements.
Stonerager- A sandigo with enhanced intellect and minor spellcasting ability. He has been defeated multiple times, but never slain. It is said he still roams the Boulderwastes, recruiting and charming other sandigos to serve him.
Talonstrike - A torquelus whose rider died. Driven mad by loss and magic, it storms across the skies. The magic's biggest effect was a breath weapon. It can shoot a beam of arcane energy from its beak. Has taken up a nest in the mountains near where its rider died, as if it still hopes that they will return.
Lecarnam: Giant serpentine creature with four wings. Their bodies are not perfect cylinders, but are slightly flat. They live up high in the upper atmoshpere, and are said to have a connection to the plane of air. They can unleash massive blasts of energy in concentrated beams if they need to, but rarely see any other living thing to use it on. They are solitary, and have a strange coating on their back and wings. They are light green, and able to photosynthesize, which allows them to live away from everything else. It is said that there is one somewhere with a whole town on it's back, with people and animals living on it's flat back. That is generally considered a fairy tale however, and none have ever seen it. In fact, they are so rare some question the existence of the Lecarnam themselves. They are real, but due to their high altitude environment they might as well not be as far as the Empire is concerned.
Kitsune: While technically arcane infused Pelise, they have become their own seperate race to the Frostundra. They are seen as omens of fortune, and symbols of the mystical. Most have very wise, peaceful personalities, but a few have gone mad from the power. Like the kitsune of Japanese myths, they have multiple tails.
Scavers: Tiny rodent people who the Frostundra believe live around them, hiding in the walls and snow. They take leftover crumbs and shed hairs. They are seen as benevolent, timid creatures.They also appear in the phrase "Clever as a Scaver", due to their adaptable, shrewd nature. In reality, they exist, but not as sentient. Just hamster like creatures who have learned to live aside the Frostundra.
Thaumpire: The Manatwister equivalent of a vampire, these creatures such the mana from mages. This leaves them as shriveled husks if they die from the drain. If they survive, the victim still appears thin and emaciated, but can be restored by replenishing their mana.