| Honorific Prefix: | Saint |
| Hilarinus | |
| Death Date: | 361 AD |
| Death Place: | Arezzo, Tuscany |
| Venerated In: | Ostia |
| Feast Day: | 16 July |
Hilarinus (or Hilary; died 361 AD) was a martyr who died with Donatus of Arezzo during the persecutions of the Roman Emperor Julian (r. 361–363). His feast day is 16 July.
The Monks of Ramsgate wrote in their Book of Saints (1921),
The Roman Martyrology mentions Hilarinus in the lives of Saints Donatus and Gallicanus,
The hagiographer Alban Butler (1710–1773) wrote in his Lives of the Fathers, Martyrs, and Other Principal Saints under August 7,