Cuckoo's Egg is a novel by science fiction and fantasy author C. J. Cherryh, set in her Alliance-Union universe. The book was published by DAW Books in 1985, and there was also a limited hardcover printing by Phantasia Press in the same year. The book was nominated for the Hugo Award and longlisted the Locus Award for Best Novel. It was later reprinted along with Cherryh's novel Serpent's Reach in the 2005 omnibus volume The Deep Beyond.
The book introduces the alien Shonunin race, and the plot of the novel concerns a male Shonun raising a human boy. The book's title is therefore a reference the practice of brood parasitism among certain species of cuckoo birds. In this practice, the cuckoos lay their eggs in other birds' nests and the unwitting hosts then expend their energy hatching the cuckoo's eggs. The metaphor is not precisely applied in this case because the Shonun in the book is knowingly and deliberately raising a human child rather than having been tricked into doing so.
In Cuckoo's Egg Cherryh adopts the less common approach in science fiction stories containing aliens of relating the story from the alien's (Shonunin) perspective, thus making the humans the aliens.
The back-story presented in the novel describes the first contact between the Shonunin and humans, which occurred when a damaged human probe with five crewmembers entered the Shonunin's home system. The contact, however, turned violent. It was not clear who fired the first shot, but the Shonunin, who had only recently put themselves into space, chased the crippled human ship for two years before overpowering it. Having suffered losses themselves, the Shonunin killed all the humans aboard. They knew the probe had been sending messages out of the solar system and the Shonunin, incapable of interstellar travel themselves, now feared retribution from the technologically superior humans.
A Shonun, Dana Duun Shtoni no Lughn (Duun), was charged with the task of saving the Shonunin world from the potential threat the humans posed. Duun's solution was to raise a human child to adulthood who could serve as an emissary to his race and hopefully prevent a major conflict when humans return to the Shonunin system. Scientists used DNA sequences from one of the dead human crewmembers to produce the male human child, whom Duun named Haras, meaning Thorn. Raising a human in their midst, an alien and the enemy, sparked fear among the Shonunin, but Duun elected to undertake the task himself, uncertain whether the creature would turn on him.