Geoffrey Monck was a powerful mage and a member of the Novigradian Union along with Jan Bekker and Giambattista. He was also an original member of the Brotherhood of Sorcerers, and one of the first humans to master the magic of the Old races. He is the author of The Magic of the Elder Folk and co-author of Natural Magic with Ivo Richert.
Geoffrey became famous because of his habit of trapping djinns in bottles and extracting three wishes out of each genie so ensnared. Apparently, he was able to conjure whirlwinds and hurricanes, as well as levitate with the help of his prisoners. He sealed each bottle with a sign depicting "a broken cross and a nine-pointed star".
In Chapter III, he is mentioned by Bras of Ban Ard while the sorcerer and Geralt are discussing Loc Muinne's history. On Iorveth's path, rescuing Philippa Eilhart during the quest The Spellbreaker reveals that she has set up residence in Monck's former home.