Katherine Irene Kurtz (born October 18, 1944) is an American fantasy writer, author of sixteen historical fantasy novels in the Deryni series, as well as occult and urban fantasy. Resident in Ireland for over twenty years, she moved to Virginia in 2007.

Kurtz was born on October 18, 1944, in Coral Gables, Florida, where she also grew up. She secured a scholarship to study chemistry and graduated with a B.S. in chemistry from the University of Miami, later attending medical school for a year and taking an M.A. in Medieval History at UCLA.^[1] While pursuing her Masters, she worked for the Los Angeles Police Academy and began writing her first novels.^[2][3] She also worked in oceanography and television.^[1]

Kurtz is best known for the Deryni novels and short stories. Her 1970 debut novel, Deryni Rising, was one of the first fantasy novels written in a mode closer to historical fiction than to mythology or legend, as was common in the then-popular high fantasy works such as those by J. R. R. Tolkien. Writing in Strange Horizons, Kari Sperring calls Kurtz the "first writer of secondary-world historical fantasy", noting her close attention to the importance of faith in pre-modern Western societies and her portrayal of magic as a formal, ritual practice as opposed to the "picaresque and informal" way magic was depicted in other fantasy of the time.^[4]

She also wrote several occult alternate history novels in her Templar series, and urban fantasy novels in her Adept series.^[4]

Kurtz has a weekly chat with her fan base about her writing, life, cats, and many other subjects.^[5]

Kurtz married Scott MacMillan in 1983; they have one son. Within the following couple of years they moved to Ireland. Both later became naturalized Irish citizens. Until 2007, they lived at Holybrooke (Hollybrook) Hall, in the largest of four houses formed from the original historic building, between Kilmacanogue and Bray in County Wicklow, Ireland. Kurtz wrote, and Macmillan, who had worked in the film industry, took a role as a herald in the Office of the Chief Herald of Ireland. They put their Irish home on the market in 2006 for 3.5 million euro,^[6] and in 2007 moved back to the United States, to a historic house in Virginia.^[7]