Julius Pollux (Greek: Ἰούλιος Πολυδεύκης, Ioulios Polydeukes; fl. 2nd century) was a Greek scholar and rhetorician from Naucratis, Ancient Egypt. Emperor Commodus appointed him a professor-chair of rhetoric in Athens at the Academy — on account of his melodious voice, according to Philostratus' Lives of the Sophists.
Pollux was the author of the Onomasticon (Ὀνομαστικόν), a Greek thesaurus or dictionary of Attic synonyms and phrases, arranged not alphabetically but according to subject-matter, in ten books. It supplies in passing much rare and valuable information on many points of classical antiquity — objects in daily life, the theater, politics – and quotes numerous fragments of lost works. Thus, Julius Pollux became invaluable for William Smith's Dictionary of Greek and Roman Antiquities, 1842, etc.
Pollux was probably the person satirized by Lucian as a worthless and ignorant person who gains a reputation as an orator by sheer effrontery, and pilloried in his Lexiphanes, a satire upon the affectation of obscure and obsolete words.
A Latin translation made by Rudolf Gwalther was published in Basel at 1541 and made Julius Pollux more available to Renaissance antiquaries and scholars, and anatomists, who adopted obscure Greek words for parts of the body.