- See Julio-Claudian family tree.
A marble bust of Caligula restored to its original colours. The colours were identified from particles trapped in the marble.
Gaius Julius Caesar (named in honor of his famous relative) was born in Antium (modern Anzio and Nettuno) on 31 August 12 AD, the third of six surviving children born to Germanicus and his second cousin Agrippina the Elder. Gaius had two older brothers, Nero and Drusus, as well as three younger sisters, Agrippina the Younger, Julia Drusilla and Julia Livilla. He was also a nephew of Claudius, Germanicus' younger brother and the future emperor.
Agrippina the Elder was the daughter of Marcus Vipsanius Agrippa and Julia the Elder. She was a granddaughter of Augustus and Scribonia on her mother's side. Through Agrippina, Augustus was the maternal great-grandfather of Gaius.
As a boy of just two or three, Gaius accompanied his father, Germanicus, on campaigns in the north of Germania. The soldiers were amused that Gaius was dressed in a miniature soldier's outfit, including boots and armour. He was soon given his nickname Caligula, meaning "little (soldier's) boot" in Latin, after the small boots (caligae) he wore. Gaius, though, reportedly grew to dislike this nickname.
Suetonius claims that Germanicus was poisoned in Syria by an agent of Tiberius, who viewed Germanicus as a political rival.
After the death of his father, Caligula lived with his mother until her relations with Tiberius deteriorated. Tiberius would not allow Agrippina to remarry for fear her husband would be a rival. Agrippina and Caligula's brother, Nero, were banished in 29 AD on charges of treason.
The adolescent Caligula was then sent to live with his great-grandmother (and Tiberius's mother) Livia. After her death, he was sent to live with his grandmother Antonia Minor. In 30 AD, his brother, Drusus Caesar, was imprisoned on charges of treason and his brother Nero died in exile from either starvation or suicide. Suetonius writes that after the banishment of his mother and brothers, Caligula and his sisters were nothing more than prisoners of Tiberius under the close watch of soldiers.
In 31 AD, Caligula was remanded to the personal care of Tiberius on Capri, where he lived for six years. To the surprise of many, Caligula was spared by Tiberius. According to historians, Caligula was an excellent natural actor and, recognizing danger, hid all his resentment towards Tiberius. An observer said of Caligula, "Never was there a better servant or a worse master!"
Caligula claimed to have planned to kill Tiberius with a dagger in order to avenge his mother and brother: however, having brought the weapon into Tiberius's bedroom he did not kill the Emperor but instead threw the dagger down on the floor. Supposedly Tiberius knew of this but never dared to do anything about it. Suetonius claims that Caligula was already cruel and vicious: he writes that, when Tiberius brought Caligula to Capri, his purpose was to allow Caligula to live in order that he "... prove the ruin of himself and of all men, and that he was rearing a viper for the Roman people and a Phaethon for the world."
In 33 AD, Tiberius gave Caligula an honorary quaestorship, a position he held until his rise to emperor. Meanwhile, both Caligula's mother and his brother Drusus died in prison. Caligula was briefly married to Junia Claudilla, in 33, though she died in childbirth the following year. Caligula spent time befriending the Praetorian prefect, Naevius Sutorius Macro, an important ally. Macro spoke well of Caligula to Tiberius, attempting to quell any ill will or suspicion the Emperor felt towards Caligula.
In 35 AD, Caligula was named joint heir to Tiberius's estate along with Tiberius Gemellus.