The favourite sister
Julia Drusilla was a daughter of Germanicus and Agrippina the Elder, and by ancient report Caligula’s favourite sister. After he became emperor in 37 CE, he granted his sisters exceptional public honours: their names were added to state oaths of loyalty, and they appeared alongside him on coinage — treatment unprecedented for women who were not emperors’ wives or mothers.
Scandal in the ancient sources
Suetonius reports allegations of an incestuous relationship between Caligula and Drusilla; the claim belongs to a hostile biographical tradition that delighted in scandalous stories about Caligula, and it cannot be independently confirmed. What is better attested is the sheer scale of public honour Caligula gave her, in life and after death.
The first Roman woman deified
Drusilla died in 38 CE. Caligula’s grief was reportedly extravagant, and he had her formally deified as Diva Drusilla — the first Roman woman to receive this honour. Her sisters, Agrippina the Younger and Julia Livilla, did not fare nearly as well under Caligula’s later, more paranoid rule.
Historical sources
Suetonius, Caligula 24
Drusilla’s relationship with Caligula, the incest allegation, and her deification.
Cassius Dio, Roman History 59.11
Public honours granted to Caligula’s sisters.
Portrait: José Luiz Bernardes Ribeiro / Wikimedia Commons, CC BY-SA 4.0. Resized for display.