Once Upon a Mattress is a musical comedy with music by Mary Rodgers, lyrics by Marshall Barer, and book by Jay Thompson, Dean Fuller, and Marshall Barer. It opened off-Broadway in May 1959, and then moved to Broadway. The play was written as a humorous adaptation of the 1835 Hans Christian Andersen fairy tale "The Princess and the Pea".

Hans Christian Andersen was a Danish author. Although a prolific writer of plays, travelogues, novels, and poems, he is best remembered for his literary fairy tales.