Ancillary Justice is a science fiction novel written by Ann Leckie. It is set in a future where an empire called the Radch controls a significant portion of the galaxy. The story follows Breq, a former starship AI who seeks revenge against the ruler of the Radch. Ancillary Justice explores themes of identity, power, and the nature of consciousness. It won several prestigious awards, including the Hugo, Nebula, and Arthur C. Clarke Awards.