Cassius Longinus was an Ancient Roman jurist and politician. A grandnephew of Servius Sulpicius Rufus and descendant of Gaius Cassius Longinus, he was also one of Caesar's assassins.
Cassius, a pupil of Sabinus, was head of the legal school called the Sabinians or Cassinians. His principal works are the libri (commentarii) iuris civilis in at least ten volumes, which only survive in quotes by later authors such as Iavolenus. He held the office of praetor, then that of consul suffectus in 30, and proconsul of Asia in 40–41, and legatus, governor of Syria in 41-49. He was exiled by Nero to Sardinia in 65 and returned to Rome under Vespasian.