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 both the Hugo Award and 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.