Bookwyrm is a dragon being from the realm of Mixed-up Fairy Tales. While not mentioned in any KQ game he appears in a couple of expanded universe articles in the InteraAction magazine that relate to Rosella and/or Graham, and other of Sierra's illustrious citizens.
Background
He once met Rosella while traversing through Daventry. She saw the dragon, sitting on a hollow log and reading. She greeted him, and asked him if he had seen her football. "I am the Bookwyrm," said the dragon. He mentioned he had indeed seen her football. He mentioned that his nemesis, the Bookend had run past carrying it. But then a tall blond man in green took it from him and ran away. This turned out to be Robin Hood.
Some time later he interviewed a much older Rosella and Graham about their favorite books. He also interviewed other individuals including Sonny Bonds, Larry Laffer, and Roger Wilco, Laura Bow, Willy Beamish who had also also met Rosella in the past. He also interviewed Robin Hood the green man he had seen take the football from Bookend. He also interviewed Patti (Larry's girlfriend) but Rosella had never met her other than in Hoyle 3 (but she and Graham had heard about from Larry once).
See also
Behind the scenes
It's interesting to note that the land of Fairy Tales from Mixed-Up Fairy Tales has characters such as Fairy Godmother, Seven Dwarves, Beauty and the Beast who also appear as characters in King's Quest. Though the characters tend to be closer to their original Fairy Tale counterparts than the versions in King's Quest realm. Beauty's father for example appears in the game, rather than Beauty being a character mixed with Cinderella.