The Enchanted Pig (Porcul cel fermecat) is a Romanian fairy tale, collected in Rumanische Märchen and also by Petre Ispirescu in Legende sau basmele românilor. Andrew Lang included it in The Red Fairy Book.
It is Aarne-Thompson type 425A, the search for the lost husband. Others of this type include The Black Bull of Norroway, The Brown Bear of Norway, The Daughter of the Skies, East of the Sun and West of the Moon, The King of Love, The Tale of the Hoodie, Master Semolina, The Sprig of Rosemary, The Enchanted Snake, and White-Bear-King-Valemon. It opens with an episode of 411, In an Enchanted Skin; others of this type include The Pig King.
A king goes to war and tells his daughters they may go anywhere in the castle except one room. One day, they disobey and find a book open in it. It says that the oldest shall marry a prince from the east, the second a prince from the west, and the youngest a pig from the north. The youngest is horror-struck, but her sisters manage to convince her that it is impossible.
The king returns and discovers, from the youngest's unhappiness, what they had done. He resolves to face it as best they can. A prince from the east marries the oldest, and a prince from the west the second, and the youngest becomes distressed. A pig comes to woo her, and when the king would have refused his consent, the city fills with pigs. The king tells his daughter that he is certain there is something strange about this pig, and that he believes magic has been at work. If she were to marry the pig, it might be broken.