Mist Bear

Like the mundane bears they resemble, a mist bear is motivated by simple pursuits, such as food. Unlike other ursines, the mist bear can dissipate into a cloud of ethereal vapor, greatly complicating the efforts of neighboring humanoids to keep their provisions safe from the creature's depredations.

Fortunately, the mist bear follows a predictable pattern of behavior, usually foraging within the Universe for only a few months every year to gorge itself. Once sated, it then enters a state similar to hibernation where it drifts through the Ethereal Plane as a cloud of intangible vapor.