The gens Cassia, nomen Cassius, was one of the oldest families of ancient Rome. The road Via Cassia that went to Arretium was built by the family. The Italian village Cassano Irpino traditionally derives its name from the gens Cassia.
- Spurius Cassius Vecellinus - early consul
- C. Cassius C.f. Longinus, consul 171 BC
- Q. Cassius Longinus, consul 164 BC
- Lucius Cassius Longinus Ravilla - consul 127 BC
- Gaius Cassius Longinus, consul 124 BC
- Lucius Cassius Longinus, consul 107 BC
- Gaius Cassius Longinus, consul 96 BC
- Gaius Cassius Longinus, consul 73 BC
- Lucius Cassius Longinus, consul 30
- Cassius Dio, consul 291
- Lucius Cassius Hemina - annalist
- Quintus Cassius Longinus - quaestor
- Gaius Cassius Longinus - tyrannicide
- Gaius Cassius Longinus - jurist
- Lucius Cassius Longinus - tribune
- Cassius Parmensis - two; jurist and tyrannicide
- Cassius Severus - orator
- Cassius Chaera - centurion
- Avidius Cassius - soldier and usurper
- Cassius Apronianus - father of Dio Cassius
- Dio Cassius Cocceianus - historian
Cassia was also one of the two oligarchic families which dominated Roman Olissipo - the present Portugese cpatial Lisbon.
