Slathe: Big enough to wrestle a mecha, and still only a mid sized creature on Actaeon. They are, however, the largest animal that has natural predators as an adult. A slathe has wooly hair, in various browns and reds that naturally locks up into a thick coat over their thicker skin. They have flat, simple faces and broad dull teeth in powerful jaws. The upper two of their four limbs are almost twice as long as the lower, and are similarly thicker as well.

They’re tree climbers, and though otherwise non-aggressive, extremely territorial of their arboreal homes.
Slathes form a symbiotic triangle with the razorleaf trees and yurgs. Their thick, matted coat allows them to hide in the branches of the enormous red razorleaf trees without getting cut, but since they can’t eat the leaves, they still have to brave the forest floor for food, making them prey for yurgs. When a yurg chases a slathe, if I they don’t get them, they’ll throw themselves against the tree, cutting themselves on the leaves. Their blood nourishes the razorleaf, giving it its color and providing it with the iron it needs to keep its leaves sharp and hard.

Yurg: Fast, mean, and dumb, yurgs are hairless, six legged predators. Their shoulders come up to just above the average man’s head. Their primary survival mechanism is to breed quickly, and throw as many of themselves at their prey as possible. Before humans came along, their primary prey were the slathes in Actaeon’s great red forests, but humans are a good deal easier to kill, even if their meat won’t go as far. They stalk human settlements, but a simple electric fence is usually enough of a deterrent, as it takes more zaps than you’d expect for one to realize that lunging at the wires won’t do it any good.
As soon as they get up to full running speed, their front arms come off the ground and they grasp at their prey with sharp claws.

Mathorn: A tall creature on six spindly legs. They are lithe and thin, and have disproportionately large horns on top of their head. Two protrusions that grow in nearly perfect fractal “snowflake” patterns, side by side so that they fan out. Their fractal horns never stop growing, but are actually living bone and scales, able to heal if damaged. A mathorn, though able to walk for short distances, moves primarily in large, flea-like bounds. The next jump in any series is notoriously hard to predict, helping to elude predators. A common Actaeon figure of speech is to say that a pointless or difficult task is “like chasing mathorn.”

Quillodon: An enormous omnivore with a mouth to match its appetite. A quillodon is covered every inch in sharp, thick spines about two meters long. Though willing to forage if necessary, it usually gets its food by picking off plants(and smaller animals) that have gotten caught on its spines as it rolls, curled into a ball, over the land. A quillodon is easily one of the worst of Actaeon’s native creatures to encroach on a human settlement. Not because they are aggressive, but because they are so large they invariably cause damage just by passing through. Fully grown, they have no natural predators, and killing one is difficult even for humans with their sophisticated weaponry. It takes force that, on any other animal, would be extreme overkill to take one down for good. It’s usually more cost effective to steer them away from settlements. It’s not like they’re hard to see coming.