Ondine is a ballet in three acts, composer Hans Werner Henze. The première of the ballet took place at the Royal Opera House, London, on 27 October 1958, with the composer as guest conductor.
Ondine bears a kind of resemblance to The Little Mermaid. The story derives from Fouqué's novella Undine, the tale of a water-nymph who marries a mortal. Similar to other 19th century fairy tales, the plot is based on man (Palemon) encountering the supernatural (the water nymph Ondine), but the outcome is rather different from many of the 19th century classics: here, it is the man that dies, and the female character survives. Ondine makes her first entrance from a fountain, shivering in the cold air as we would in water. She meets the hero, Palemon, and is astonished when she feels his heartbeat as she doesn't possess a heart. Palemon deserts Berta, whom he has been courting, and decides to marry Ondine. During a particularly strong storm while at sea, Ondine is lost overboard. Palemon survives the shipwreck created by the angry Ondines and believing Ondine is lost ends up marrying Berta. Ondine returns and is heartbroken when she discovers Palemon's unfaithfulness. When she kisses him, he dies and she brings his body back into the sea with her forever.
In the published score, as with the title of the ballet, Henze also retained the original spellings of the character names. The London ballet production was given as Ondine, but the score was titled Undine, and names the lead character as Undine. Henze also uses the original name Beatrice rather than Berta.