Julius Julianus (fl. 315–325) was a politician of the Roman Empire, related to the Constantinian dynasty.
He served Licinius as praetorian prefect from at least spring 315 to September 324, until Constantine I definitively defeated Licinius. However, the fall of Licinius did not mark the end of Julianus' career, as Constantine had praised Julianus' administration of the State and chose him, in 325, as suffect to replace a consul fallen in disgrace, Valerius Proculus.
He was the father of Basilina, wife of Constantine's half brother Julius Constantius and mother of Emperor Julian, and of the mother of Procopius; he was probably related to Eusebius of Nicomedia. Julianus was the master of the Gothic philosopher slave Mardonius, who was the teacher of both Basilina and Julian.
- Libanius, Orations 18.9
- Salway, Benet (2008). "Roman consuls, imperial politics, and Egyptian papyri: the consulates of 325 and 344 CE". Journal of Late Antiquity. 1 (2): 278–310. Retrieved Apr 18, 2019.
- Timothy David Barnes, Constantine and Eusebius, Harvard University Press, 1981, ISBN 0-674-16531-4, pp. 70, 214.
- Robert Browning, The Emperor Julian, University of California Press, 1978, ISBN 0-520-03731-6, p. 32.
Flavius Julius Crispus Caesar III,
Flavius Claudius Constantinus Caesar III
| Consul of the Roman Empire
with Sextus Anicius Faustus Paulinus
Flavius Valerius Constantinus Augustus VII,
Flavius Julius Constantius Caesar