Emhyr var Emreis

Emhyr var Emreis is the emperor of Nilfgaard, the most powerful nation in Witcher Saga. He's the main antagonist of the books and a major antagonist of the games.

He is publicly favourable to the Elder Race, unlike to the Northern Monarchs. In Witcher 2 Emhyr sent Letho, Serrit and Egan to assassinate kings of North, so he could easily conquer the whole North. In Witcher 3 he took over both Aedirn and Temeria during the Third Northern War.