Around the start of the Common Era, the family trees of the gens Julia and the gens Claudia became intertwined into the Julio-Claudian family tree as a result of marriages and adoptions.

Gaius Octavius was a Roman politician. He was an ancestor to the Roman emperors of the Julio-Claudian dynasty. He was the biological father of the emperor Augustus, step-grandfather of the emperor Tiberius, great-grandfather of the emperor Claudius, and great-great grandfather of the emperors Caligula and Nero. Hailing from Velitrae, he was a descendant of an old and wealthy equestrian branch of the plebeian gens Octavia. Not being of senatorial rank, he was a novus homo at Rome. His grandfather, Gaius Octavius, fought as a military tribune in Sicily during the Second Punic War. His father, Gaius Octavius, was a municipal magistrate who lived to an advanced age.