Baigujing (Chinese: 白骨精) is a yaoguai from the novel Journey to the West. The name is translated into English as White Bone Spirit in the William John Francis Jenner translation. Bai Gu Jing is a shapeshifting demoness, and in her true form she is depicted as a skeleton.
Baigujing was a demon who desired to eat the flesh of Xuanzang. She disguised herself as a village girl and offered him and his disciples poisonous fruits. Due to her strong powers, no one could detect that she was a demon except Sun Wukong. He hit her with his staff, seemingly killing her. Sun Wukong tried to explain to everyone what she was but they didn't believe him. Xuanzang believed she was an innocent and buried her. Having survived the attack, she dug under ground to recover. She returned a second time disguised as an elderly woman. She lies to the group, causing them to believe that the village girl from earlier was her daughter. Sun Wukong sees through her disguise once again and kills her. The group is angered at Sun Wukong and continues to not believe him. She returns a third time as an elderly man who lies about having a daughter and wife. The group immediately felt guilty as they believed they are the two women Sun Wukong had slain. She taunts Sun Wukong into attacking her by using her powers, and only he could hear her. Having a short-temper, he finally beats her with his staff and kills the demon, revealing that she was just a skeleton spirit. Sun Wukong shows this to Xuanzang, who initially believes him, but Zhu Bajie convinces Xuanzang that Sun Wukong transformed the corpse into a skeleton to evade the Band-tightening spell. Xuanzang is angry at Sun Wukong at his reckless slaying and scolds him. He cuts his ties with Sun Wukong and sends him away. Hurt by his master's words, Sun Wukong leaves and returns to Water Curtain Cave. In his absence, Xuanzang gets caught by another demon that Zhu Bajie and Sha Wujing could not defeat, and Zhu Bajie was forced to invite Sun Wukong back to save Xuanzang.
- Wu Cheng-en: Journey to the West, chapter 27.