Former name: Gaius Octavius

Thumbnail sketch: First emperor of Rome; reigned for about 40 years. Livia's second husband; Julia's father; Tiberius' and Drusus' stepfather; Octavia's brother; Marcellus' uncle.

Risk factors: No sons and an ambitious wife with two sons of her own!

Portrayed by: Brian Blessed

Whom you may also remember from: "Star Wars, Episode I", "The Black Adder", "Robin Hood: Prince of Thieves", "Flash Gordon", several fine Shakespearean films.

Full name: Livia Drusilla

Thumbnail sketch: Augustus' second wife and his Empress; Tiberius' and Drusus' mother; Claudius' grandmother.

Risk factors: The Emperor's wife has two sons of her own, but the Emperor's fertile daughter has sons.

Portrayed by: Siân Phillips

Whom you may also remember from: "Dune", "Jennie: Lady Randolph Churchill", "Clash of the Titans", "La Femme Nikita" (TV).

Full name: Octavia Thurina Minor

Thumbnail sketch: Much-loved sister of the Emperor; mother of Marcellus and Antonia.

Risk factors: A jealous sister-in-law.

Portrayed by: Angela Morant

Whom you may also remember from: "The Imaginatively Titled Punt & Dennis Show", BBC's Lord Peter Wimsey series.

Full name: Marcus Claudius Marcellus

Thumbnail sketch: The Emperor's nephew and son-in-law; son of Octavia and her first husband; husband of Julia; half-brother of Antonia.

Risk factors: A jealous and ambitious step-aunt.

Portrayed by: Christopher Guard

Whom you may also remember from: "The Lord of the Rings" 1978 animated film as the voice of Frodo, many British television programs.

Full name: Julia Augusti Filia (or Julia the Elder)

Thumbnail sketch: Daughter of Augustus Caesar by a previous marriage; stepdaughter and daughter-in-law to Livia; widow to Marcellus and Agrippa; wife to Tiberius; mother of Gaius, Lucius, Postumus, Agrippina, and Julia the Younger (Julilla).

Risk factors: A jealous stepmother.

Portrayed by: Frances White

Whom you may also remember from: "A Very Peculiar Practice", "Dangerfield".

Full name: Marcus Vipsanius Agrippa

Thumbnail sketch: Augustus' greatest friend, his commander of the fleet against Antony and Cleopatra in the Battle of Actium, and in time his son-in-law.

Risk factors: Augustus' wife Livia is jealous of anyone who poses a threat to her son Tiberius' chances at the Imperial throne.

Portrayed by: John Paul

Whom you may also remember from: "Doomwatch".

Full name: Lucius Julius Caesar

Thumbnail sketch: Grandson and adopted son of Emperor Augustus; son of Marcus Agrippa and Julia; brother of Gaius, Agrippina, and Postumus; half-brother to Vipsania (Tiberius' first wife).

Risk factors: Livia. You'll find that Livia is a risk factor to a lot of these characters, one way or the other.

Portrayed by: Simon MacCorkindale

Whom you may also remember from: "Manimal", "Poltergeist: The Legacy", "Casualty".

Full name: Marcus Vipsanius Agrippa Postumus

Thumbnail sketch: Grandson of Emperor Augustus; son of Marcus Agrippa and Julia; brother of Gaius, Agrippina, and Postumus; half-brother to Vipsania (Tiberius' first wife).

Risk factors: Again, Livia. Even though Postumus has not been formally adopted by Augustus out of his respect for the continuation of his late friend Agrippa's family line, he is much more favored by Augustus than Livia's son Tiberius...and thus a threat to Tiberius' chances of becoming Emperor.

Portrayed by: John Castle

Whom you may also remember from: "The Lion in Winter", "Blow-Up", "Casualty".