Yamauba (山姥, 山うば, or 山女郎), yamamba, and yamanba are variations on the name of a yōkai found in Japanese folklore. Mostly said to resemble women, yamauba may be depicted as predatory monsters or benevolent beings.

Depending on the text and translator, the yamauba often appears as a monstrous crone, "her unkempt hair long and golden white ... her kimono filthy and tattered", with cannibalistic tendencies.

The yamauba is said to have a mouth at the top of her head, hidden under her hair. In one story, it is revealed that her only weakness is a certain flower containing her soul.

The people attacked by yamauba in folklore are typically travelers and merchants (such as ox drivers, horse drivers, coopers, and notions keepers) who often travel along mountain paths and encounter people in the mountains, so they are also thought to be the ones who had spread such tales.

In one tale, a mother traveling to her village is forced to give birth in a mountain hut assisted by a seemingly kind old woman, only to discover too late that the stranger is a yamauba, with plans to eat her helpless son Kintarō. In another story, the yōkai raises the orphan hero Kintarō, who goes on to become the famous warrior Sakata no Kintoki.

Yamauba have been portrayed in two different ways. There were tales where men stocking oxen with fish for delivery encountered yamauba at capes and were chased by them, such as the Ushikata Yamauba and the Kuwazu Jobo, as well as a tale where someone who was chased by a yamauba would climb a chain appearing from the skies in order to flee, and when the yamauba tried to make chase by climbing the chain too, she fell to her death into a field of buckwheat, called the "Tendo-san no Kin no Kusari". In these tales, the yamauba is a fearsome monster trying to eat humans.

On the other hand, there are tales such as the Nukafuku Komefuku (also called "Nukafuku Kurifuku"), where two sisters out gathering fruit meet a yamauba who gives treasure to the kind older sister (who was tormented by her stepmother) and curses the ill-mannered younger sister with misfortune. There is also the "Ubakawa" tale, where a yamauba gives a human good fortune.

In the town of Masaeki (now Ebino) in Nishimorokata District, Miyazaki Prefecture, a yamahime (山姫; mountain princess) would wash her hair and sing in a lovely voice. Deep in the mountains of Shizuoka Prefecture, there is a tale that the yamahime would appear as a beautiful woman around twenty years of age, with black hair and an unusually coloured kosode. When an armed hunter found her and shot at her, she would catch the bullet with her hands.