Cahir Mawr Dyffryn aep Ceallach

Cahir Mawr Dyffryn aep Ceallach, or simply Cahir, is not identified by name at all in Blood of Elves. It only, in later novels, becomes clear that he is the black knight with the bird of prey wings on his helmet who invades Ciri's dreams. He was sent by Emhyr var Emreis, the emperor of Nilfgaard to find Ciri.