Katherine (Irene) Kurtz (born 18 October 1944) is the author of numerous fantasy novels, most notably the Deryni novels. Although born in America, for the past several years, up until just recently, she has lived in a castle in Ireland. She now lives in Virginia.
She was a member of the Swordsmen and Sorcerers' Guild of America (SAGA), a loose-knit group of Heroic Fantasy authors founded in the 1960s, some of whose works were anthologized in Lin Carter's Flashing Swords! anthologies. She also was an early member of the Society for Creative Anachronism; in her persona of Bevan Fraser of Stirling she achieved the rank of Countess, ruling the Kingdom of the West as Queen Consort for one reign in the 1970s.
Source: Wikipedia, "Katherine Kurtz", available under the CC-BY-SA License.