Kingslayers

The Assasins of Kings are a mysterious organization of witcher-like mutants.

The Witcher
In The Witcher outro, Foltest, king of Temeria is attacked by a masked assassin, and is defended by Geralt. This assassin is very skilled and fights using two swords. The battle is pitched and the outcome does not seem at all certain, but at the last moment, Geralt throws his recently acquired coin purse at the villain. This ploy startles the assailant sufficiently to allow the witcher an unparried blow, which he lands with aplomb, severing one of the attacker's arms.

In the aftermath, both Geralt and king Foltest take a closer look at the villain's face which has now been unmasked. Inexplicably, the man appears to have the same eye mutation as Geralt ... to be continued...

The Witcher 2: Assassins of Kings
In the sequel, The Witcher 2: Assassins of Kings, it seems that the Assassins will become the main antagonist. One of them can be seen in the leaked video.