The Deryni Series is a collection of fantasy novels written by author Katherine Kurtz. Set in the fictional medieval kingdom of Gwynedd, the series explores the lives of the Deryni, a race of people with psychic abilities and magical powers. The storylines often revolve around themes of political intrigue, religious conflict, and the struggle for acceptance in a society that fears and misunderstands the Deryni. The series began with the novel Deryni Rising, published in 1970, and has since expanded to include several sequels and prequels. The books are known for their rich world-building and complex characters, making them a significant contribution to the fantasy genre.