Dionysius Thrax, a Hellenistic grammarian and a pupil of Aristarchus of Samothrace, has lived and worked in Alexandria but later teaches at Rhodes (around 144 BCE).

The brief but comprehensive Art of Grammar, the first extant grammar of Greek, is attributed to him but many scholars today doubt that the work really belongs solely to him due to the difference between the technical approach of most of the work and the more literary approach (similar to the second century's Alexandrian tradition) of the first few sections.

It concerns itself primarily with a morphological description of Greek, concerned with basic word-forming elements and dictating the order in which topics are to be treated, but lacks any treatment of syntax.

The work will be translated into Armenian and Syriac in the early Christian era.