Dionysius of Halicarnassus (Greek: Διονύσιος Ἀλεξάνδρου Ἁλικαρνᾱσσεύς Dionysos Alexandrou Alikarnasseus; "Dionysios son of Alexandros of Halikarnassos"; c. 60 BC – after 7 BC) was a Greek historian and teacher of rhetoric, who flourished during the reign of Caesar Augustus. His literary style was Atticistic — imitating Classical Attic Greek in its prime.
Dionysius' opinion of the necessity of a promotion of paideia within education, from true knowledge of Classical sources, endured for centuries in a form integral to the identity of the Greek elite.
He was a Halicarnassusian. At some time he moved to Rome after the termination of the civil wars, and spent twenty-two years studying Latin and literature and preparing materials for his history. During this period, he gave lessons in rhetoric, and enjoyed the society of many distinguished men. The date of his death is unknown. In the 19th century, it was commonly supposed that he was the ancestor of Aelius Dionysius of Halicarnassus.
His major work, entitled Ῥωμαϊκὴ Ἀρχαιολογία (Rhōmaikē archaiologia, "Roman Antiquities"), embraced the history of Rome from the mythical period to the beginning of the First Punic War. It was divided into twenty books, of which the first nine remain entire, the tenth and eleventh are nearly complete, and the remaining books exist in fragments in the excerpts of the Roman emperor Constantine Porphyrogenitus and an epitome discovered by Angelo Mai in a Milan manuscript. The first three books of Appian, Plutarch's Life of Camillus and Life of Coriolanus also embody much of Dionysius.