The Tale of the Moon Cuckoo (Mongolian: Saran kökögen-ü namtar) is a traditional Mongolian opera by the composer, writer, and incarnate lama Dulduityn Danzanravjaa, composed between 1831 and 1832 and first performed in 1833. It tells the story of a prince who is tricked into being a cuckoo by a manipulative companion, who then impersonates the prince and causes the decline of their kingdom.
A significant work of Mongolian theatre, the Tale of the Moon Cuckoo is unrelated to Western opera and was significantly influenced by the Tibetan tradition of lhamo. Danzanravjaa based the opera's story on a 1737 Tibetan work of the same name, and combined Tibetan elements with Chinese costuming and Buddhist philosophical concepts. Performed by at least eighty-seven actors in a specially designed theatre, the Tale of the Moon Cuckoo lasted for a month and was interspersed with unrelated comedic or educational pieces. It was performed for many years after Danzanravjaa's death in 1856 until the Communist purges in the 1930s.