Octavia (born c. 69 bc—died 11 bc) was the full sister of Octavian (later the emperor Augustus) and wife of Mark Antony.
Octavia was the daughter of Gaius Octavius and his second wife, Atia. Before 54 bc Octavia was married to Gaius Marcellus, by whom she had two daughters and a son. On the death of Marcellus in 40 she was married to Mark Antony, who at the time was ruling the Roman state with Octavian and Marcus Aemilius Lepidus. At first this marriage helped to reduce tensions between Antony and Octavian, and when the two rulers quarreled in 37, Octavia brought about peace between them, which resulted in the Treaty of Tarentum. But in 36 Antony left Italy to command troops in Parthia and while in the East resumed his liaison with the Egyptian queen Cleopatra. Although Octavia brought troops and money to him (35), he refused to see her, and in 32 he obtained a divorce. Octavia was a faithful wife and mother who raised Antony’s children by Cleopatra along with her own children. After the death of her son Marcellus in 23, she withdrew from public life. The Porticus of Octavia in Rome is named for her.