|Cover artist||John Harris|
|6 October 2015|
|Preceded by||Ancillary Sword|
Ancillary Mercy is a science fiction novel by the American writer Ann Leckie, published in October 2015. It is the final novel in Leckie's "Imperial Radch" space opera trilogy, which began with Ancillary Justice (2013) and was followed by Ancillary Sword (2014).
While searching Athoek Station's slums, Fleet Captain Breq finds someone who appears to be an ancillary from a ship that has been hiding beyond the Radch's reach for three thousand years. Meanwhile, Translator Zeiat, a messenger from the alien and mysterious Presger empire arrives, as does Breq's enemy, the reactionary faction of the divided Anaander Mianaai – ruler of an empire at war with herself.
Anaander captures Athoek Station and executes members of its governing body on a live newsfeed. After this incident, Breq forges an alliance with the AI in charge of Athoek Station and begins work to disable Anaander's ships and render Station and other AIs immune to her overrides. She returns to Athoek Station and confronts Anaander with the aid of Zeiat. During the confrontation, she claims that AIs are independent, autonomous, and sentient species distinct from humanity, and thus protected by the terms of humanity's treaty with the Presger. Unwilling to risk violating the treaty, Anaander is forced to retreat.
Kirkus Reviews says the novel "Wraps up the story arc with plenty of room to tell many more tales in this universe. Let's hope Leckie does." The reviewer appreciated how the novel shows that a small group of people can affect a galaxy-spanning empire, and the delivery of the message was deft and meaningful.