O-Ren Ishii is a fictional character from the film series Kill Bill, directed by Quentin Tarantino. She is portrayed by actress Lucy Liu and is known for her fierce demeanor and exceptional sword-fighting skills. O-Ren is a member of the Deadly Viper Assassination Squad and serves as one of the main antagonists in the story. In the film, O-Ren's backstory reveals her traumatic childhood and rise to power in the criminal underworld. She becomes the leader of the Tokyo Yakuza and is characterized by her cold, calculating nature and strong sense of honor. O-Ren's character is a blend of traditional Japanese culture and modern violence, making her a memorable figure in the series.