Vattier de Rideaux
The intelligence chief was one of the organizers the attack by the Scoia'tael on the mages' conference on Thanedd Island. Because the attack did not achieve its primary objective, de Rideaux and the emperor came to the conclusion that there were traitors among them, namely: Vilgefortz, Rience, Cahir and possibly Isengrim Faoiltiarna.
The Nilfgaardian ambassador Shilard Fitz-Oesterlen and Letho talk about Vattier. The latter reveals to Geralt that Vattier succeeded in obtaining information from Yennefer about the Lodge of Sorceresses. Apparently, only Vattier, Imperator Emhyr var Emreis, and Letho know of the plan to destabilize the Northern Kingdoms through regicide.
In the journal notes concerning spy Hendrik's fate, Dandelion calls Vattie de Rideaux "chief of imperial spy corps" and mentions that he would "surely beamed with pride" if he ever heard that Hendrik was loyal to Nilfgaard till the very end. Hendrik preferred to die in agony rather than reveal where he hid his reports about Ciri.