Caligula’s family tree is the Julio-Claudian dynasty, the first imperial family of Rome, and he was its third emperor, ruling from 37 to 41 CE. He was the son of Germanicus and Agrippina the Elder, making him the great-grandson of Augustus through both his mother and his father.
The Julio-Claudian Dynasty: An Overview
The Julio-Claudian dynasty ruled Rome from 27 BCE, when Augustus became the first emperor, until 68 CE, when Nero died. The name comes from two intertwined families: the Julii (descended from Aeneas and, by claim, the goddess Venus) and the Claudii (an old patrician family). Augustus, a Julian by adoption, married Livia, a Claudia, and their descendants and adopted heirs formed the dynasty. The five emperors of this line were Augustus, Tiberius, Caligula, Claudius, and Nero. Caligula was the first emperor actually born into the family, rather than adopted into it, which was a key part of his appeal when he took the throne.
Caligula’s Parents: Germanicus and Agrippina the Elder
Caligula’s father, Germanicus, was a hugely popular general and the adopted son of Emperor Tiberius. Germanicus was himself the son of Nero Claudius Drusus (brother of Tiberius) and Antonia Minor (daughter of Mark Antony and Octavia, Augustus’s sister). This made Germanicus the nephew of Tiberius and the grandson of Augustus’s sister, so he was a Julian on his mother’s side and a Claudian on his father’s side.
Caligula’s mother, Agrippina the Elder, was the daughter of Marcus Vipsanius Agrippa (Augustus’s closest friend and general) and Julia the Elder (Augustus’s only natural daughter). That made Agrippina the granddaughter of Augustus, and her marriage to Germanicus united the Julian and Claudian lines even more tightly. Their children, including Caligula, were therefore descended from Augustus through both parents—a rare double claim to the throne.
Caligula’s Siblings and Their Fates
Germanicus and Agrippina the Elder had nine children, but only six survived infancy. Caligula was the third son, born on 31 August 12 CE. His siblings were:
- Nero Caesar (born 6 CE) and Drusus Caesar (born 8 CE): the two older brothers, both adopted by Tiberius and both died in exile or prison in the 30s CE, victims of the political purges led by Sejanus, Tiberius’s praetorian prefect.
- Agrippina the Younger (born 15 CE): Caligula’s younger sister, who later became the mother of Emperor Nero. She was exiled by Caligula in 39 CE, then returned under Claudius and eventually married him.
- Drusilla (born 16 CE): Caligula’s favorite sister. He deified her after her death in 38 CE, and there were rumors (probably exaggerated) that they had an incestuous relationship. She was married to Marcus Aemilius Lepidus, who was executed for conspiracy in 39 CE.
- Julia Livilla (born 18 CE): the youngest sister, exiled by Caligula in 39 CE and later executed under Claudius’s wife Messalina.
Caligula also had two younger brothers who died in infancy, and his mother Agrippina the Elder died in exile in 33 CE, reportedly by starvation, after Tiberius accused her of treason.
Caligula’s Wives and Children
Caligula married four times, but his marriages were short and he left only one known child. His wives were:
- Junia Claudilla (married around 33 CE): she died in childbirth in 36 CE, and the child also died.
- Livia Orestilla (married and divorced in 37 CE): Caligula reportedly took her from her own wedding to Gaius Piso, then divorced her days later.
- Lollia Paulina (married and divorced in 38 CE): a wealthy noblewoman, whom Caligula divorced because she was barren.
- Milonia Caesonia (married in 39 CE): a woman much older than Caligula, already pregnant with his child. They had a daughter, Julia Drusilla, born in 39 CE. The child was killed along with her parents in January 41 CE, when Caligula was assassinated.
Caligula’s only child, Julia Drusilla, was named after his dead sister. She was about two years old when she was murdered, and with her death, Caligula’s direct line ended.
Caligula’s Grandparents and Great-Grandparents
To see the full tree, you have to go back two generations. On his father’s side, Caligula’s grandparents were:
- Nero Claudius Drusus (38–9 BCE), the younger brother of Tiberius and a celebrated general who died in Germany. He was the son of Livia and her first husband, Tiberius Claudius Nero.
- Antonia Minor (36 BCE–37 CE), the younger daughter of Mark Antony and Octavia, Augustus’s sister. She was known for her virtue and lived to see her grandson Caligula become emperor.
On his mother’s side, his grandparents were:
- Marcus Vipsanius Agrippa (63–12 BCE), Augustus’s closest friend and the man who won the naval battle of Actium for him. He married Augustus’s daughter Julia.
- Julia the Elder (39 BCE–14 CE), Augustus’s only natural child. She was exiled by her father for adultery in 2 BCE.
His great-grandparents on the Julian side were Augustus himself and his wife Livia, though Augustus was not Livia’s biological father. Caligula’s biological great-grandfather on his mother’s side was Agrippa, and on his father’s side, it was Tiberius Claudius Nero (Livia’s first husband).
How Caligula Became Emperor
Caligula was not the obvious heir. When Tiberius died in 37 CE, the succession was unclear. Tiberius had adopted his grandson Gemellus and his grand-nephew Caligula jointly, but Caligula was the older and far more popular. The Roman Senate and the Praetorian Guard acclaimed him as emperor, and he quickly had Gemellus killed. Caligula’s popularity came from being the son of Germanicus, who was still adored by the people and the army. His early reign was generous and popular, but within a year he fell seriously ill, and after his recovery his behavior became erratic and cruel, leading to his assassination in 41 CE.
Common Misconceptions About Caligula’s Family
A frequent error is that Caligula was the son of Tiberius. He was not; Tiberius was his great-uncle and adoptive grandfather. Another misconception is that Caligula’s sister Drusilla was his wife. She was not; she was married to Lepidus, and the incest claims come from later historians like Suetonius, who wrote decades after Caligula’s death and often repeated scandalous gossip. Also, Caligula is often said to have made his horse a consul, but the ancient sources actually say he planned to make his horse Incitatus a consul, and there is no evidence he ever did. His family tree is often drawn incorrectly because the Julio-Claudian family intermarried so heavily that many members were related through multiple lines—Caligula, for instance, was both the great-grandson and the grand-nephew of Augustus.
Frequently Asked Questions
Who were Caligula’s parents?
His parents were Germanicus and Agrippina the Elder. Germanicus was a famous general and the adopted son of Tiberius, while Agrippina was the granddaughter of Augustus. Both were beloved by the Roman people, and their popularity was a major reason Caligula was welcomed as emperor.
Was Caligula related to Julius Caesar?
Yes, but only by marriage and adoption, not by blood. Julius Caesar was the great-uncle of Augustus, who adopted Augustus as his son. Augustus then passed the Julian name to his daughter Julia, whose daughter Agrippina the Elder was Caligula’s mother. So Caligula was a Julian through his mother, but he had no direct blood descent from Julius Caesar himself.
Did Caligula have any children who survived?
No. His only known child was a daughter, Julia Drusilla, born in 39 CE to his fourth wife Milonia Caesonia. She was killed in 41 CE, at about two years old, when Caligula was assassinated. There were no other surviving children.
Why did Caligula’s family have so many deaths?
The Julio-Claudian family was plagued by political violence. Tiberius’s reign saw many executions of potential rivals, including Caligula’s brothers and his mother. Caligula himself executed or exiled several relatives, and his own assassination led to the murder of his wife and daughter. The dynasty’s constant fear of conspiracy and succession struggles caused most of these deaths.
Who succeeded Caligula?
His uncle, Claudius, succeeded him. Claudius was the younger brother of Germanicus, making him Caligula’s paternal uncle. He was found hiding behind a curtain after Caligula’s murder and was proclaimed emperor by the Praetorian Guard. Claudius was the fourth emperor and the father of Nero, the last of the Julio-Claudian line.
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