Lucius Cassius Longinus was the first husband of the Emperor Caligula's sister Julia Drusilla in 33 AD. Cassius came from an ancient and noble gens, the Cassii. In early 37, he was appointed by Tiberius as a commissioner. When Tiberius died later that year, Caligula became Caesar. Caligula ordered Cassius to divorce Drusilla so that she could marry Marcus Aemilius Lepidus. Caligula subsequently murdered Cassius, before his own assassination in 41, based on an oracle which Caligula interpreted as indicating that Cassius would assassinate him.
By a strange coincidence, Caligula was assassinated by a Cassius, the tribune Cassius Chaerea.