Full sister to Augustus, Octavia was the only daughter born of Gaius Octavius' second marriage to Atia Balba Caesonia, niece of Julius Caesar. Octavia was born in Nola, present-day Italy; her father, a Roman governor and senator, died in 59 BC from natural causes. Her mother later remarried, to the consul Lucius Marcius Philippus. Octavia spent much of her childhood travelling with her parents. Marcius was in charge of educating Octavia and her brother Augustus.
Before 54 BC her stepfather arranged for her to marry Gaius Claudius Marcellus Minor. Marcellus was a man of consular rank, a man who was considered worthy of her and was consul in 50 BC. He was also a member of the influential Claudian family and descended from Marcus Claudius Marcellus, a famous general in the Second Punic War. In 54 BC, her great uncle Caesar is said to have been anxious for her to divorce her husband so that she could marry Pompey who had just lost his wife Julia (Julius Caesar's daughter, and thus Octavia's cousin once removed). The couple did not want to get a divorce so instead Pompey declined the proposal and married Cornelia Metella. So Octavia's husband continued to oppose Julius Caesar including in the crucial year of his consulship 50 BC. Civil war broke out when Caesar in Gaul invaded Italy in 49 BC.
Marcellus, a friend of Cicero, was an initial opponent of Julius Caesar when Caesar invaded Italy, but did not take up arms against his wife's great uncle at the Battle of Pharsalus, and was eventually pardoned by him. In 47 BC he was able to intercede with Caesar for his cousin and namesake, also a former consul, then living in exile. Presumably, Octavia continued to live with her husband from the time of their marriage (she would have been about 15 when they married) to her husband's death when she was about 29. They had three children: Claudia Marcella Major, Claudia Marcella Minor and Marcus Claudius Marcellus. All three were born in Italy. Her husband Marcellus died in May 40 BC.
By a Senatorial decree, Octavia married Mark Antony in October 40 BC, as his fourth wife (his third wife Fulvia having died shortly before). This marriage had to be approved by the Senate, as she was pregnant with her first husband's child, and was a politically motivated attempt to cement the uneasy alliance between her brother Octavian and Mark Antony; however, Octavia does appear to have been a loyal and faithful wife to Antony. Between 40 and 36 BC, she travelled with Antony to various provinces and lived with him in his Athenian mansion. There she raised her children by Marcellus as well as Antony's two sons; the two daughters of her marriage to Antony, Antonia Major and Antonia Minor, were born there.
The alliance was severely tested by Antony's abandonment of Octavia and their children in favor of his former lover Queen Cleopatra VII of Egypt (Antony and Cleopatra had met in 41 BC, an interaction that resulted in Cleopatra bearing twins, a boy and a girl). After 36 BC, Octavia returned to Rome with the daughters of her second marriage. On several occasions she acted as a political advisor and negotiator between her husband and brother. For example in the spring of 37 BC, while pregnant with her Antonia Minor, she was considered essential to an arms deal held at Tarentum, in which Antony and Augustus agreed to aid each other in their Parthian and Sicilian campaigns. She was hailed as a "marvel of womankind." Mark Antony divorced Octavia in 32 BC. In 35 BC, after Antony suffered a disastrous campaign in Parthia, she brought fresh troops, provisions, and funds to Athens. There Antony had left a letter for her, instructing her to go no further. Following Antony's rejection of her, their divorce, and his eventual suicide in 30 BC, Octavia became sole caretaker of their children as well as guardian of Antony's children from his unions with both Fulvia and Cleopatra:
Octavia did not marry a third time.
Virgil reading Aeneid
, Book VI, to Augustus and Octavia, by Taillasson
In 35 BC Augustus accorded a number of honours and privileges to Octavia, and Augustus's wife Livia, previously unheard of for women in Rome. They were granted sacrosanctitas, meaning it was illegal to verbally insult them. Previously this had been only granted to tribunes. Livia and Octavia were made immune from tutela, the male guardianship which all women in Rome except for the Vestal Virgins were required to have. This meant they could freely manage their own finances. Finally they were the first women in Rome to have statues and portraits displayed en masse in public places. Previously only one woman, Cornelia, mother of the Gracchi, had been part of the public statues displayed in Rome. In Augustus's rebuilding of Rome as a city of marble, Octavia featured. In all her representations she wore the "nodus" hairstyle, which at the time was considered conservative and dignified, and worn by women from many classes. .
Augustus adored, but never adopted, her son Marcellus. When Marcellus died of illness in 23 BC unexpectedly, Augustus was thunderstruck, Octavia disconsolate almost beyond recovery.
Aelius Donatus, in his Life of Vergil, states that Virgil
recited three whole books [of his Aeneid] for Augustus: the second, fourth, and sixth—this last out of his well-known affection for Octavia, who (being present at the recitation) is said to have fainted at the lines about her son, "… You shall be Marcellus" [Aen. 6.884]. Revived only with difficulty, she sent Virgil ten thousand sesterces for each of the verses."
She may have never fully recovered from the death of her son and retired from public life, except on important occasions. The major source that Octavia never recovered is Seneca ("Cons ad Marcia", II.) but Seneca may wish to show off his rhetorical skill with hyperbole, rather than adhere to fact. Some dispute Seneca's version, for Octavia publicly opened the Library of Marcellus, dedicated in his memory, while her brother completed the Marcellus's theatre in his honor. Undoubtedly Octavia attended both ceremonies, as well as the Ara Pacis ceremony to welcome her brother's return in 13 from the provinces. She was also consulted in regard to, and in some versions advised, that Julia marry Agrippa after her mourning for Marcellus ended. Agrippa had to divorce Octavia's daughter Claudia Marcella (Major) in order to marry Julia, so Augustus wanted Octavia's endorsement very much.
Octavia died of natural causes. Suetonius says she died in Augustus's 54th year, thus 10 BC with Roman inclusive counting. Her funeral was a public one, with her sons-in-law (Drusus, Ahenobarbus, Iullus Antony, and possibly Paullus Aemillius Lepidus) carrying her to the grave in the Mausoleum of Augustus. Drusus delivered one funeral oration from the rostra; Augustus the other and gave her the highest posthumous honors (e.g. building the Gate of Octavia and Porticus Octaviae in her memory). Augustus also had the Roman senate declare his sister to be a goddess. Augustus declined some other honors decreed to her by the senate, for reasons unknown. She was one of the first Roman women to have coins minted bearing her image; only Antony's previous wife Fulvia pre-empted her.