Named by descendants of those held in Chinese internment camps before the Great War, yao guai are mutated American black bears and one of the more vicious creatures of the wasteland, sporting razor sharp claws and teeth, and a nasty temperament.
Yao guai are large, mutated ursines that are descended from the bears that lived across America before the Great War. They are able to reproduce, as evidenced by the presence of cubs and some have extended lifespans, such as the pre-War circus bear, Ruzka. Wild yao guai will attack nearly any other animals or people they encounter, including deathclaws. Despite this, yao guai exhibit a gentle, familial bond toward one another when found together and can even be domesticated.
The physical build of the Zion variant does not drastically deviate from pre-War bears as much as the yao guai in the Capital Wasteland and the Commonwealth. Comparatively, they are overall less dog-like in their posture and movement and sport thicker patches of fur and more body fat. Since their upper body, chest and arms are not as massive, the Appalachian yao guai have a more traditional bear-like posture and gait. These yao guai are generally larger than their unmutated predecessors and are more aggressive.
Yao guai are extremely fast and powerful creatures, second only to deathclaws in terms of raw strength and speed. Unlike deathclaws, they are less alert, as the player character may come in contact with one when it is asleep or lying down. Yao guai do not attack bighorners in Zion Canyon. The Animal Friend perk does not affect them and they will become hostile towards the player character upon detection.
Giant yao guai are larger versions of yao guai. A giant yao guai is a sigficicant threat to low level player characters. Early in the Honest Hearts add-on, a giant yao guai attacks and kills a green gecko on top of a rock while the player approaches the Dead Horses camp. A few of these can be found near the Red Gate.