From A Wiki of Ice and Fire
|Allegiance||Maesters of the Citadel|
|Book(s)|| The World of Ice and Fire (Mentioned)|
A Feast for Crows (Mentioned)
Archmaester Walgrave is an elderly archmaester of the Citadel. He has lost his wits. His ring, rod and mask are made of black iron. He often calls Pate by the name "Cressen", suggesting that he worked with Maester Cressen in the past.
He was considered by many to have the foremost knowledge in ravencraft and wrote a book about the subject called Black Wings, Swift Words.  He taught Maester Yandel how to read. However he is now an old man and keeps the title archmaester only by courtesy, his wits having left him a long time ago. Maester Gormon now judges in his place. Pate was assigned to help him.