Hilarianus or Hilarian may refer to:
People Publius Aelius Hilarianus (2nd century), Roman politician, probably the governor in the Passion of Saints Perpetua and Felicity (2nd century), Roman military commander Mecilius Hilarianus (fl. 316–354), prefect of Rome and praetorian prefect of Italy (fl. 377–396), prefect of Rome and praetorian prefect of Italy Decimius Hilarianus Hesperius (4th century), Roman politician Caelius Hilarianus (fl. 377), Roman senator and priest Hilarianus (magister officiorum) (fl. 470) Quintus Julius Hilarianus (fl. 397), Roman historian and millenarian writer (d. 793), Catholic priest purportedly martyred by the Saracens
Other , genus of insects
See also Hilarion (name) Hilarinus Hilarius