Vilgefortz is one of the main antagonists of the Witcher book series, first appearing in the second book. He was a member of the Chapter of Sorcerers, but he conspired with Emhyr var Emreis, the emperor of Nilfgaard.
Alliance with Emhyr
After Emhyr, going under the alias of Duny, decided to bring his daughter Ciri back to Nilfgaard, he conspired with Vilgefortz. Due to his past encounters with mages, Vilgefortz was the only mage Emhyr trusted, because the later made clear that he expected to be rewarded with lands and titles and did not plot a bigger plan. Vilgefortz created a giant teleporter, that sucked ships sailing near it into it and teleported them to the outskirts of Castle Stygga, his main base. The ship indeed got sucked in, but Pavetta, sensing that Emhyr planned somethin, had smuggled Ciri ofboard previously.
After Emhyr's return to Nilfgaard, Vilgefortz helped Emhyr rise to the throne, using intrigues and his genial intellect. In exchange, Emhyr promised him the North, once it was taken over.
At Thanedd Island
Geralt first met Vilgefortz at the Island Thanedd, where Vilgefortz wants to talk to him in private. Vilgefortz told him about his past, that he was raised by druids after the death of his parents, and that he only became a mage when he was a grown man. He himsellf recalled being ashamed of the things he has done, including robbing people and killing. At the end, he was running to the other end of the world from the executioner's axe. There, he met a woman. He had a short romance with her, yet later he left her to join the mages.He offered Geralt to become a mage as well, though Geralt denied him. Vilgefort then told him that he would need to take sides soon.
This happened earlier than Geralt expected.Unbeknownst to him, the banquet preceding the reunion on Thanedd began quietly enough with mages discussing their alliances with either the Northern Kingdoms or Nilfgaard, or professing neutrality but things soon began to heat up.
Mages employed by Nilfgaard, led by Vilgefortz, had planned a sneak attack on their northern counterparts. The Northern supporters caught wind of the treachery and quietly tried to restrain the enemy mages before the plan could be executed, with the help of Dijkstra and his men.
However, due to actions of Tissaia de Vries (who was acting only in a manner she considered fair and impartial) he broke free and a battle between the mages of both fractions began. Vilgefortz followed Ciri to the Tor Lara, but he crossed paths with Geralt, who stood between him and Ciri. Vilgefortz materialized an iron staff inside his hands. Believing Vilgefortz to be easily beatable, Geralt engaged in a fight with the mage, but was brutally beaten and almost killed by Vilgefortz. Vilgefortz only let Geralt live because he wanted to catch upt to Ciri and told Geralt to see it as a lecture. Vilgefortz then went to the Tor Lara but when Ciri used the portal inside the tower blew up, the resulting blast disfigures Vilgefortz' face and costs him an eye. Vilgefortz retreated, not only hunted by the Northern Kingdoms and the newly founded Lodge of Sorceresses, but only by Nilfgaard because he betrayed Emhyr by delivering a false Ciri (because he needed the true one for himself).
Continuing his plans
Unable to contact Nilfgaard again because he sent Emhyr a false Ciri, Vilgefortz instead sends his apprentice Rience to contact Stefan Skellen, who alongside a group of conspirators plans to kill the emperor. Skellen, his group and Rience continue hunting down Ciri (thought opposed to Skellen, Rience wants to capture Ciri alive). During the journey Rience stays in contact with Vilgefortz through a magical communication device but at one point the device malfunctions, which leads to Rience and Skellen believing that Vilgefortz has given them up, although he is just not able to contact them. Ironically, the device starts working again just after Ciri has abushed the group on an icy lake, leading to the deaths of Rience and almost all of Skellens men.
After Yennefer has sailed from Skellige into the teleporter of Vilgefortz, she falls into the mages hands. Vilgefortz imprisons her at Castle Stygga, where Yennefer sees that the explosion of Tor Lara caused grave injuries to Vilgefortz, scarring and burning half of his face and destroying one of his eyes (although he was in the process of magically regrowing it).
Ciri later appeared at Stygga to save Yennefer, but was captured and imprisoned by Vilgefortz. Vilgefortz told her that as many others, he wanted to use her blood but unlike the others, he didn't plan to make a son with her but wanted to use the powers on himself and Ciri wouldn't need to be alive for it.
Showdown at Castle Stygga
However, before Vilgefortz could continue his plans, he was alarmed that Geralt and his companions had arrived at the castle. Vilgefort left the room to assist Bonhart and Skellen in the fight. Fights broke out in many parts of the castle. Vilgefortz encountered both Geralt and Yennefer, fighting the latter in a magical duel and almost killing her. However, before he can kill Yennefer, Geralts vampire companion Regis intervenes, scratching Vilgefortz just under his newly created eye. In return, Vilgefortz rips the vampire apart with his bare hands and then burns the body, melting him and almost killing him. Geralt then fights Vilgefortz. Unbeknownst to Vilgefortz, Geralt uses an amulet which creates an illusion of Geralt. Vilgefortz knocks the false Geralt to the ground and delivers the finishing blow, but is perplexed when the attack goes right through him. Realising he has been tricked, Vilgefortz tries to attack the place where he believes the true Geralt to be, but is cut down by the witcher. Before dying, Vilgefortz madly screams Geralts name and is then finished off.
After the battle, Yennefer remarks that she was only able to fight Vilgefortz for so long because his coordination was off due to his injured eye.
The Witcher 2: Assassin of Kings
The Witcher 3: Wild Hunt