Illwhyrin is the primary antagonist from the 1995 Capstone videogame Witchaven.
On the Isle of Char, Illwhyrin has situated herself in the heart of a subterranean caverns and has unleashed a horde of monsters. All the human inbitants on Char are slaughtered and ritually sacrificed, save Lord Verkapheron, who flees to summon help from Grondoval of Stazhia.
Illwhyrin prepares the power to destroy the dimension barrier (called the Rift) which separates the Realm from the demonic Nether Reaches, with the intent on letting countless demons overwhelm the human world.
Grondoval fights his way through Illwhyrin's caverns, having small encounters with her throughout, before finally facing her in a fierce battle in her lair and slaying her.
With her defeat, Lord Verkapheron is free to reclaim his place on Char. Illwhyrin's death would soon invoke the wrath of her sister Cirae-Argoth.