Daenys Targaryen

Daenys Targaryen, known as the Dreamer, was a former member of House Targaryen who lived at the time of the Scourge of Valyria. She is said to have had clairvoyant abilities, which allowed her to predict the Scourge of Valyria twelve years before it occurred. Her father, Aenar Targaryen, took her, the rest of her family and five dragons to Westeros, to the island of Peyredragon. 

Daenys became the wife of her brother Gaemon Targaryen, who succeeded Aenar as head of House Targaryen. They had two children together: Aegon and Elaena.

She wrote Signs and Omens (when she was still a virgin), a work presumed lost but of which three pages are quoted by Archmaester Marwyn in his Book of Lost Books.