Julia Antonia Major (Latin for "the older") (b. August/September 39 BC) was a daughter of Mark Antony and Octavia, the sister of Augustus Caesar. Little is known of this elder daughter of Mark Antony and Octavia, shadowed as she is by her younger sister Antonia Minor, who mothered the emperor Claudius as well as being grandmother to the emperor Caligula and great grandmother to Nero.

She married Lucius Domitius Ahenobarbus. Their son Gnaeus Domitius Ahenobarbus married Agripinilla, becoming parents to Roman Emperor Nero. Their daughters Domitia and Domitia Lepida married Marcus Valerius Messalla Barbatus, becoming parents to Messalina. The latter married Emperor Claudius and bore him two children Britannicus and Octavia.