Juan María Montalvo Fiallos (April 13, 1832–January 17, 1889) was an Ecuadorian author and essayist, generally thought to be one of Ecuador's best writers of the period. A political liberal, Montalvo's beliefs were marked by anti-clericism and a keen hatred for Ecuador's two caudillos that ruled during his life: Gabriel García Moreno and Ignacio de Veintemilla. After an issue of his book, El Cosmopolita, viciously attacked Moreno, Montalvo was exiled to Colombia, where he would write most of his later works. He was a dedicated champion of democracy, was said to have a lucid and inquisitive intellect and a strong, semi-romantic temperament.
His 1880 book Catilinarias made him famous throughout intellectual circles in the United States, Europe and the rest of Latin America. Alongside full length books, Montalvo was an accomplished essayist, and his Siete Tratados (1882) and Geometría Moral (published in 1902, after his death) were popular in Ecuador and were banned by Veintemilla.
He also wrote a witty sequel to Miguel de Cervantes's Don Quixote, called Capítulos que se le Olvidaron a Cervantes ("Chapters Cervantes Forgot"). Juan Montalvo died of tuberculosis in Paris, France. His mummified body now rests in a mausoleum in his birthplace of Ambato.