Diogenianus, of Heraclea on the Pontus (or in Caria), Greek grammarian, flourished during the reign of Hadrian.

He was the author of an alphabetical lexicon, chiefly of poetical words, abridged from the great lexicon of Pamphilus of Alexandria (AD 50) and other similar works. It was also known by the title ***** (for the use of "industrious poor students"). It formed the basis of the lexicon, or rather glossary, of Hesychius of Alexandria, which is described in the preface as a new edition of the work of Diogenianus.

We still possess a collection of proverbs under his name, probably an abridgment of the collection made by himself from his lexicon (ed. by E Leutsch and FW Schneidewin in Paroemiographi Graeci, 1. 1839). Diogenianus was also the author of an Anthology of epigrams, of treatises on rivers, lakes, fountains and promontories; and of a list (with map) of all the towns in the world.