Xuannü 玄女, the Mysterious Maiden, or Taixuannü 太玄女, the Maiden of the Great Mystery, also called Jiutian Xuannü 九天玄女, Jiutiannü 九天女, Jiutian Niangniang 九天娘娘 or Yuannü 元女, is a legendary Daoist immortal living at the celestial court of the Yellow Emperor 黃帝.
It is believed she had a human head, but the body of a bird (ren shou niao xing 人首鳥形), and was a teacher of the Yellow Emperor. An ancient text called Huangdi wen Xuannü bingfa 黃帝問玄女兵法 says that during the Yellow Emperor's long-lasting fight against this opponent Chi You 蚩尤, he was defeated in nine battles. Yet after being instructed by the Mysterious Maiden on Mt. Taishan 太山 in a three days and three nights long session, he finally defeated Chi You in the Battle of Zhuolu 涿鹿. The Maiden had supported him with the means of liuren 六壬 and dunjia 遁甲 divinations, "military tallies" (bingfu 兵符), maps and strategies (tuce 圖策), and seals and swords (yinjian 印劍), as well as with 80 ox-skin drums (kuiniu gu 夔牛鼓, see kui 夔).
This story is narrated in the apocryphal texts Longyu hetu 龍魚河圖 and Huangdi chu zao jue 黃帝出早決, the story collections Huangdi neizhuan 黃帝內傳, Guangchengzi zhuan 廣成子傳, Guang bowuzhi 廣博物志 and Shanhaijing 山海經, but also in the universal history Shiji 史記 and the Daoist encyclopaedia Yunji qiqian 雲笈七籤.
The latter also says that the Mysterious Maiden was a disciple of the Shengmu Yuanjun 聖母元君 (the Daoist form of the Queen Mother of the West 西王母).
Younger stories hold that her worldly name was Zhuan He 顓和. She lost her parents in early childhood and was herself predicted a short lifespan, and therefore decided to contemplate on the mystical dao 道. She became a student of Master Jade 玉子 from which she learned to dive into the water without drowining and bearing the greatest coldness in winter. She was also able to walk around in palaces and houses like a spectre. Her study was deep in the mountains, where stone cliffs opened to let her inside, where she had her living quarters. She was able to control 36 different techniques, like creating fire blazes or changing the size of objects. One day she ascended to Heaven and became an immortal.
There were numerous shrines for the Mysterious Maiden throughout China, for instance, Niangniang Miao 娘娘廟 in Beijing (close to Asian Games Village). A Shrine of the Mysterious Maiden is mentioned in the romances Shuihuzhuan 水滸傳 and Fengshen yanyi 封神演義 and other stories, where the Maiden appears in the dreams of protagonists.
The Mysterious Maiden is also the teacher of the Yellow Emperor in instructing him in the nine coital positions in the eroticist classic Xuannüjing jiushi 玄女經九式 (or Sunüjing 素女經). Another book called Xuannüjing 玄女經 is a prognostication text concerned with auspicious days for marriage.