Eutropius (died 399) was a fourth-century Eastern Roman official.
Eutropius was born in one of the Roman provinces of the middle east, either Assyria or on the border of Armenia. According to Honorius' court poet Claudian, who composed a satirical invective against Eutropius due to the latter's hostility to Claudian's patron, Stilicho, Eutropius served successively as a catamite, pimp, and body-servant to various Roman soldiers and nobles, before winding up among the domestic eunuchs of the imperial palace. After Theodosius' death in 395 he stood at the head of a faction opposed to the powerful Praetorian Prefect of the east, Rufinus, and successfully arranged the marriage of the new emperor, Arcadius, to Aelia Eudoxia, having blocked an attempt by Arcadius' chief minister to increase his power by marrying the young and weak-willed emperor to his daughter. After Rufinus' assassination that same year, Eutropius rose in importance in the imperial court, and he soon became Arcadius' closest advisor. His ascension to power was assisted by his defeat of a Hun invasion in 398. The next year he became the first eunuch to be appointed a consul, but his enemies Gaïnas, the magister militum at the time, and Eudoxia, the very empress he had installed, engineered his downfall that very year.
After Eutropius's fall from power, John Chrysostom's pleas kept him alive for a short time; he was eventually executed before the year ended.
During his rise to the consulship, Eutropius earned a notoriety for cruelty and greed. He may also have played a role in the assassination of his predecessor Rufinus.