Ancillary Mercy is a science fiction novel by the American writer Ann Leckie, published in October 2015. It is the conclusion of Leckie's "Imperial Radch" space opera trilogy, which began with Ancillary Justice (2013), followed by Ancillary Sword (2014). Three other novels, Provenance (2017), Translation State (2023), and Radiant Star (2026), and two short stories, "Night's Slow Poison" and "She Commands Me and I Obey", are set in the same fictional universe.