Drusus Caesar[i] (c. AD 8 – 33) was the grandson by adoption and heir of the Roman emperor Tiberius, alongside his brother Nero.

Born into the prominent Julio-Claudian dynasty, Drusus was the son of Tiberius' general and heir, Germanicus.

Sejanus, the prefect of the Praetorian Guard, had become powerful in Rome and is believed by ancient writers such as Suetonius and Tacitus to have been responsible for the downfall of Drusus the Younger.

Drusus was later imprisoned following similar charges as his brother, and remained in prison from AD 30 until his death three years later.

Drusus had eight siblings: four brothers (Tiberius and Gaius, who died young; Nero Julius Caesar; and another Gaius, nicknamed "Caligula"), three sisters (Agrippina the Younger, Julia Drusilla, and Julia Livilla), and a brother or sister of unknown name (normally referenced as Ignotus).

In October AD 14, Germanicus received a delegation from the Senate giving its condolences for the death of Augustus.

Augustus had died in August and Tiberius became emperor, making Germanicus heir to the empire.

[13][14] At the direction of Tiberius, Germanicus was dispatched to Asia to reorganize the provinces and assert imperial authority there.

However, after two years in the east, Germanicus came at odds with the governor of Syria, Gnaeus Calpurnius Piso.

[23][24] Ancient sources say the cause of death was poison, whereas modern authors, such as Barbara Levick, suggest that it may have been due to illness.

Drusus received the toga virilis and was promised the rank of quaestor five years before the legal age, just as his brother Nero had been given.

At that time, Clementia was considered a virtue of the ruling class, for only the powerful could give clemency.

[31] Tiberius found it necessary to repeat his charges, and when he did, the Senate no longer delayed; and the fate of Agrippina and Nero was sealed.