Roman historian whose work, though not completely preserved, is important for Hellenistic studies.

Trogus was a Vocontian Gaul from Gallia Narbonensis whose grandfather gained Roman citizenship (and the name Pompeius) from Pompey (Pompey the Great) and whose father was secretary to Julius Caesar (Caesar, Julius). Trogus wrote a zoological work, De animalibus, in at least 10 books, which is quoted by the elder Pliny (Pliny the Elder), and a history, Historiae Philippicae, (“Philippic Histories”) in 44 books, so called because the Macedonian empire founded by Philip II is its central theme. This work treated the ancient kingdoms from Assyria and Persia to Macedonia and the Hellenistic monarchies, followed by Parthia, Rome under the kings, and Gaul and Spain. In contrast to Livy's tradition, his perspective is cosmopolitan and Greek, not patriotic and Roman. The original work is lost, but its character is conveyed in Justin's Epitome, which preserves one-sixth of the original, the prologi (or summaries of books), and some fragments.