U'uulions

The U'uulion are a race of night creatures that originate from another world. They have no natural predators here on Umbriel, and will go out of their way to kill a human. Their skin is black with white markings, and their eyes glow red when exposed to light. They can communicate telepathically with others of their kind. When threatened, they will attack by spitting poison at their enemies.
It is believed the Thay were destroyed by the U'uulions.
The U'uulions are intelligent, but not particularly bright. They live in small groups called "clans." Clan members share a common ancestor, which means they all look alike. This makes it easy for them to identify each other. Clans tend to stay together, even if they're far apart.
The U'uulions eat insects, plants, and carrion. They prefer meat, especially human flesh. They'll kill any animal they come across, regardless of whether it's edible. They don't seem to care about what happens to the animals after they've killed them.
The U'uulions are a nomadic race. They move from place to place, following the seasons. During warm months, they wander through forests and plains looking for prey. In winter, they migrate to caves and abandoned mines. They spend the cold months hibernating inside their homes.
The U'uulions are extremely aggressive. If they spot a person, they won't hesitate to attack. They're also very territorial. They'll fight to the death to defend their homes and families.