Cor was the queen of the island of Coregos during the time of Prince Inga and King Rinkitink.
Cor is the wife of Gos, the king of nearby Regos. She is so stern and cruel that the people of the twin islands could not decide which of their sovereigns they dreaded most. (Rinkitink in Oz)
In their marriage, Gos is the brawn and Cor is the brains. In his later novel The Magical Mimics in Oz, Jack Snow modeled his King Umb and Queen Ra, rulers of Mount Illuso, on Gos and Cor.