Flavius Eusebius (died c. 350) was a Roman military officer and politician.
He is usually identified as the father of Eusebia, and consequently as the posthumous father-in-law of the Roman emperor Constantius II.
Born in Thessalonica to a family of Macedonian descent, Eusebius served prior to 347 as the Magister equitum et peditum in the east, probably under the emperor Constantius II.
[1] During his time as military commander, he intervened in Armenia, possibly to suppress the revolt of Bacour.
[2] After he had retired from this post, he held the rank of Comes and was made consul posterior alongside Vulcacius Rufinus in 347.