William R. Forstchen (born 1950) is an American historian and speculative fiction author, best known for his post-apocalyptic novel One Second After. He holds a Ph.D. in military history and teaches at Montreat College in North Carolina. His writing blends historical insight with thrilling narratives, often exploring themes of survival, technology, and societal collapse. Forstchen has authored over forty books, including the Lost Regiment series and collaborations with Newt Gingrich on alternate history novels.