Emile Gaboriau (1833-1873) is an important figure in the history of detective fiction. A French journalist and novelist, he created the "roman policier" with a series of books involving private detective Monsieur Lecoq, who works logically. Lecoq was based on a real-life thief turned policeman named Francois Vidocq (1775-1857), whose memoirs mixed fiction and fact.
Gaboriau's huge following was eclipsed by Arthur Conan Doyle's Sherlock Holmes. Interestingly, Holmes may have been at least partly based on another of Gaboriau's characters, consulting detective Father Tabaret, whose methods Monsieur Lecoq adopts in the first Lecoq book.