The name Herennius may refer to:

• Herennius Pontius (fl. c. 340 BC), Samnite statesman, father of Gaius Pontius
• Marcus Herennius (consul 93 BC)
• Gaius Herennius (otherwise unknown), addressee of the book Rhetorica ad Herennium
• Marcus Herennius Picens (consul 34 BC)
• Herennius Senecio (died c. 90), Roman writer, biographer of Helvidius Priscus
• Herennius Philo, also known as Philo of Byblos (c. 64–141), scholar
• Lucius Herennius Saturninus, suffect consul in AD 100
• Publius Herennius Dexippus (c. 210–273), the Greek historian most often known as Dexippus
• Herennius (fl. c. 240), a Neoplatonic philosopher; see Ammonius Saccas
• Herennius Modestinus (fl. c. 250), Roman jurist
• Herennius Etruscus (c. 227–251), Roman emperor

• Herennia Etruscilla, the mother of Herennius Etruscus
• Herennia gens, all people who had the gentilicium Herennius in their name.