Patrick Ness's 2011 fantasy novel A Monster Calls is about a thirteen-year-old boy who learns to overcome his denial about his mother's terminal cancer. Haunted by a nightmare in which his dying mother slips from his grasp as she falls off a cliff, the boy is visited by a yew tree growing in a nearby churchyard that transforms into a monster. After the monster tells the boy three parables that illustrate the inherently complex truth of human existence, the boy accepts his contradictory feelings of wanting his mother to live while simultaneously wishing for an end to both her and his suffering. In its depiction of a boy privately struggling with the anger, isolation, and denial that result from his mother's diagnosis, A Monster Calls has been praised as a lesson in accepting the unfair truths of life and death.
Ness based the novel on an idea by the late children's author Siobhan Dowd, who conceived of the story's premise while battling cancer herself. After Dowd's death in 2007, her publisher arranged for Ness to write what would have been her fifth book. In his author's note, Ness writes that Dowd "had the characters, a premise, and a beginning. What she didn’t have, unfortunately, was time." Ness says his only guideline was to write a book he thought Dowd would have liked.
Upon publication, the novel received rave reviews and Ness was awarded the Carnegie Medal and Greenaway Medal for excellence in children's literature. Ness adapted the screenplay for A Monster Calls, which was released as a film of the same name in 2016.