Gary Caplan was born in Philadelphia and earned three bachelor's degrees from the University of Pittsburgh, later earning M.D. and M.P.H. degrees. He serves as a colonel and preventive medicine officer in the reserves and has published articles in medical journals. Caplan became interested in reading science fiction and fantasy books as a young man and, after practicing medicine for several years, began to write his own fiction. At first strictly a hobby, his writing flourished and he decided to publish both a science fiction and sword and sorcery novels in his spare time.
