Who killed the eight-tailed fox in Wu Jie?

Not killed. According to the information in Qidian's novel "I take Fox Fairy Town as a Hundred Ghosts", it shows that Eight-tailed Fox Fairy is the heroine, a monster in the wild, and has not been killed. In order to repay the kindness of her previous life, she chose to take possession of Wu Jie's newborn body and protect Wu Jie with her life to help him resist the 18th robbery of fate. "I am a Ghost in Fox Fairy Town" tells the story that Wu Jie committed 18 robberies in his life and gave birth to a demon fetus. He was a strong man in a previous life. On the day he was born, 19 lightning struck around Wu Jie's yard, and a fortune teller predicted that someone else would die or Wu Jie would die himself.