Hilarius is the given name of:

• Hilarius of Aquileia (died c. 284), saint, bishop of Aquileia, Italy
• Hilarius or Hilary of Poitiers (c. 310 – c. 367), Bishop of Poitiers and Doctor of the Church
• Hilary the Deacon (Latin: Hilarius Diaconus) (fl. 355), Sardinian deacon of the Roman church
• Hilarius, Archbishop of Tarragona (Spain) c. 402
• Hilarius or Hilary of Arles (c. 403–449), Bishop of Arles and saint
• Hilarius (praefectus urbi), praefectus urbi (prefect of Rome) in 408
• Pope Hilarius or Hilary (died 468), Catholic pope and saint
• Hilarius (poet) (fl. 1125)
• Hilarius Breitinger (1907–1994), German Franciscan prelate
• Hilarius Gilges (1909–1933), Afro-German actor and communist
• Hilarius Moa Nurak (1943–2016), Roman Catholic bishop
• Hilarius of Sexten (secular name Christian Gatterer) (1839–1900), Austrian Capuchin theologian

• Hilary (name)