EWoT: Birlen Pena
Birlen Pena is an Aes Sedai of the Black Ajah. She was first mentioned in Verin Mathwin's book, naming her to be a Darkfriend. It is unknown which of the seven Ajahs she also belongs to.
She escapes from the White Tower after Egwene al'Vere becomes Amyrlin Seat, and avoids re-swearing on the Oath Rod.