A central character in Shakespeare's "Twelfth Night," Olivia is a countess admired by Malvolio, Sir Andrew, and Duke Orsino. However, Olivia falls in love with Cesario, the identity with which Viola disguises herself whilst shipwrecked in Illyria. Olivia mistakenly marries Sebastian, Viola's twin brother, and the two are happy, as the twins are extremely similar in looks and personality.

Character in Samuel Richardson's The History of Sir Charles Grandison (1754).

A highly lauded London actress, Oldfield was among the highest paid of her profession during her time.

John O’Keefe was an Irish librettist and playwright. He wrote the comic operas The Castle of Andalusia (1782) and Fontainbleau (1784). He also wrote the play Wild Oats, or The Strongest Gentlemen (1791).

A Greek mythological figure who rises from being an orphan to become King of Thebes, but in doing so inadvertently fulfills a prophecy in which he kills his father and sleeps with his mother, as recounted in Sophocles' tragedy Oedipus Rex.

Hero of Homer's Odyssey, which recounts the adventures of this Ithacan king during his decade-long return from the ten year Trojan War.

Odin (from Old Norse Óðinn, "The Furious One") is a significant deity in most if not all branches of Germanic mythology, especially in the Norse mythology branch of Germanic mythology. Among his many attributes, he is associated with wisdom, healing, poetry, frenzy, war, and death.

Elder sister of first Roman Emperor Augustus, fourth wife of Mark Antony, and great-great-grandmother of Emperor Nero, also known as "Octavia the Younger." Octavia was revered for her humanity, nobility, and depiction of traditional Roman femininity. Octavia helped to secure peace between her brother and husband as they ruled the Roman state. In 36 B.C.E., Mark Antony left for a military excursion in the East, and while gone, he resumed relations with his former wife, Cleopatra VII of Egypt, leaving Octavia to rule their children alone, heartbroken.

English translator, lawyer, military officer, and justice of the peace, whose 1579 translation of Plutarch's Parallel Lives became the main source for many of Shakespeare's Roman plays.

English bibliographer and antiquarian, best remembered for his Biographia Britannica (1747-1766).