Lucius Cassius Longinus was a Roman senator, who was active during the reigns of Tiberius and Caligula. He was ordinary consul in the year AD 30 with Marcus Vinicius as his colleague. Longinus came from an ancient and noble gens, the Cassii. He is best known as the first husband of the Emperor Caligula's sister Julia Drusilla, whom he married in 33.