This article contains information, pictures or media from non-canonical sources. To find out more about what is considered canon see LOTR:Canon
Idis was the daughter of Theoden and Elfhild in an early draft of Lord of the Rings but was soon forgotten and removed once Theoden adopted Eomer and Eowyn. She had no other mention in any of Tolkien's writings.
She is non-canonical as she was scrapped from the books.