Octavia, the feminine form of Octavius, was a name given to any girl child of the Octavian clan. From the same root as octave and October it
means 'the eighth' as in 'the eigth child'. In Roman history, there are two Octavias that stand out.
The first Octavia (ca 69 BC - 11 BC) was the grandniece of Julius Caesar and older sister of Gaius Octavius, who later became Emperor Augustus. Her first husband was Gaius Marcellus, who died in 40 BC. She wedded Marc Antony in the same year to seal the peace treaty between him and her brother. The marriage ended after a few years when Marc Antony deserted her for Cleopatra, and so did the peace.
Octavia stayed in Rome and reared children, both her own and others': two daugthers and a son called Marcus by Galius Marcellus; her daughters by Marc Antony, Antonia the Elder and Antonia Augusta (the Younger); as well as Marc Antony's son by Fulvia, Antyllus, and his children by Cleopatra: Cleopatra Selene, Alexander Helios and Ptolemy Philadelphus.
The second Octavia (32 - 62 AD) was the daughter of Emperor Claudius I and Valeria Messalina. She married the Emperor's adopted son Nero in 53. When Nero wanted to marry his mistress Poppaea he not only divorced her, but accused her of adultery and had her put to death on the island of Pandateria.