Cleitarchus, one of the historians of Alexander the Great, son of Demon, also an historian, was possibly a native of Egypt, or at least spent a considerable time at the court of Ptolemy Lagus.
Quintilian (Instit. x. I. 74) credits him with more ability than trustworthiness, and Cicero (Brutus, II) accuses him of giving a fictitious account of the death of Themistocles. But there is no doubt that his history was very popular, and much used by Diodorus Siculus, Quintus Curtius, Justin and Plutarch, and the authors of the Alexander romances. His unnatural and exaggerated style became proverbial.
The fragments, some thirty in number, chiefly preserved in Aelian and Strabo, will be found in C. Muller's Scriptores Rerum Alexandrii Magni (in the Didot Arrian, 1846); monographs by C. Raun, De Clitarcho Diodori, Curtii, Justini auctore (1868).
Cleitarchus' own book is now lost, but it was the source of Diodorus of Sicily's Library of world history and the History of Alexander the Great of Macedonia by Curtius Rufus.
Another aspect of Cleitarchus' work that deserves to be mentioned, is the psychological portrait of Alexander, which is painted in dark shades.
In Cleitarchus' opinion, the young king was corrupted by his constant good fortune and became an alcoholic, a tyrant, and a murderer.
Aeschines says, that a talent from Cleitarchus was part of the bribe which he alleges that Demosthenes received for procuring the decree in question.
Cleitarchus appears therefore to have come into the above project of Demosthenes and Callias, to whom he would naturally be opposed ; but he thought it perhaps a point gained if he could get rid of the remnant of Athenian influence in Eretria.
On this, Cleitarchus and Philistides, the tyrant of Oreus, sent ambassadors to Athens to prevent, if possible, the threatened invasion; arid Aeschines, at whose house the envoys were entertained, appears to have supported their cause in the assembly.