Gnaeus Domitius Ahenobarbus (c. 2 BC – January AD 41) was a member of the imperial Julio-Claudian dynasty of Ancient Rome.

Domitius was the son of Antonia Major (daughter of emperor Augustus' sister Octavia Minor and her second husband Mark Antony).

Although some historians such as Ronald Syme have argued that the Domitius who served with Gaius Caesar may have been an older brother of his and not Nero's father.

[6] Gaius Stern claims that the Eastern expedition is actually that of Germanicus in AD 17–19, if one assumes his birth to be in 2 BC and still interpret the violent actions to belong to Nero's father.

Domitius married his first cousin once removed Agrippina the Younger, Caligula's sister, after her thirteenth birthday in AD 28.

According to Suetonius, when Domitius was congratulated by his friends for the birth of his son he replied that any child born to him and Agrippina would have a detestable nature and become a public danger, a fact that became true during the second part of Nero's reign.

He was accused of being the accomplice of Albucilla in the crimes of adultery and murder, and also of incest with his sister Domitia Lepida, and narrowly escaped execution only because of the death of Tiberius.