Undine (EWN-dee-nuh), a water spirit, daughter of a Mediterranean water prince and foster daughter of a poor fisherman and his wife. Fifteen years earlier, she appeared, as a child of three or four, at the fisherman’s cottage shortly after the disappearance of his young daughter. She is now a beautiful young woman but rebellious, mischievous, and wildly capricious. When Huldbrand mentions Bertalda in telling his adventures, Undine bites him out of jealousy. After she and Huldbrand are married and the priest tells her to attune her soul to her husband’s, she becomes a submissive, loving wife. She generously consents to have the rejected Bertalda live at Ringstetten. On a trip down the Danube, when Huldbrand angrily calls her a sorceress, she disappears into the water. After Huldbrand’s marriage to Bertalda, Undine appears to him and embraces him until he dies. Following his burial, she becomes a spring that almost encircles his grave, thus embracing him forever.
Sir Huldbrand von Ringstetten
Sir Huldbrand von Ringstetten (HEWLD-brahnd fon RIHNG-sta-tan), a knight, wealthy, handsome, and a model of all knightly virtues except that of constancy of heart. Though forewarned against marrying Bertalda, he does so. His spirit wife, released from the fountain in which she lives, then claims him eternally.
Kuhleborn (KEW-luh-bohrn), Undine’s uncle, a water spirit who appears sometimes to mortals as a tall man dressed in a white mantle and in various other disguises. He warns Huldbrand to protect Undine and reveals to Undine the secret of Bertalda’s birth. He mischievously interferes many times in the lives of Undine, Huldbrand, and Bertalda.
Bertalda (bahr-TAHL-dah), a beautiful but haughty lady loved by Huldbrand. She is the foster daughter of a powerful duke and his duchess but the real daughter of Undine’s foster parents, who lost her shortly before Undine came to them. Bertalda is shocked and angry to learn of her humble origin. After she has been turned out by her foster parents, she acquires some humility, but her haughtiness occasionally returns.
Father Heilmann (HIL-mahn), an old priest who marries Undine and Huldbrand, refuses to unite Huldbrand and Bertalda, and administers the burial service for Huldbrand.