Quintus Curtius Rufus was a Roman historian, probably of the 1st century, author of his only known and only surviving work, Historiae Alexandri Magni, "Histories of Alexander the Great", or more fully Historiarum Alexandri Magni Macedonis Libri Qui Supersunt, "All the Books That Survive of the Histories of Alexander the Great of Macedon." Much of it is missing. Apart from his name on the manuscripts, nothing else certain is known of him. This fact alone has led philologists to believe that he had another historical identity, to which, due to the accidents of time, the link has been broken. A few theories exist. They are treated with varying degrees of credibility by various authors. Meanwhile, the identity of Quintus Curtius Rufus, historian, is maintained separately.