Full name: Tiberius Claudius Drusus Nero Germanicus

Thumbnail sketch: Fourth Roman Emperor, reigned 13 years. Son of Drusus and Antonia; grandson of Livia; nephew of Tiberius; brother of Germanicus and Livilla; uncle of Caligula and Drusilla; husband of Urgulanilla, Aelia, and Messalina; husband and uncle of Agrippinilla; great-uncle, stepfather, and adoptive father to Nero; father of Britannicus and Octavia the Younger.

Risk factors: Blind spot for his youngest and prettiest wife.

Portrayed by: Derek Jacobi

Whom you may also remember from: "Cadfael", "Little Dorrit", "Dead Again", several fine movies based on the works of Shakespeare.

Full name: King Agrippa I

Thumbnail sketch: One of the tetrarchs of the Biblical Herod family; educated in Rome; friend to Claudius and Castor; king of Judea.

Risk factors: The fickle friendship and support of Emperors and kings; high ambition for his own portion of wealth and power.

Portrayed by: James Faulkner

Whom you may also remember from: "Bridget Jones's Diary", "Bridget Jones 2", "Still Crazy Like a Fox".

Full name: Aelia Paetina

Thumbnail sketch: Adoptive sister of Sejanus; second wife of Claudius; mother of Claudia Antonia (historical figure not mentioned in the series "I, Claudius").

Risk factors: Opportunistic sister of Sejanus and unwitting co-conspirator.

Portrayed by: Liane Aukin

Full name: Valeria Messalina

Thumbnail sketch: Daughter of Domitia Lepida Minor and Marcus Valerius Messalla Barbatus. A distant cousin from Augustus' family. Wife of Claudius and Empress of Rome. Mother of Britannicus and Octavia.

Risk factors: Reckless, easily bored, and outrageously promiscuous.

Portrayed by: Sheila White

Whom you may also remember from: "Oliver!", "Z Cars", "The Spaceman and King Arthur".

Full name: Domitia Lepida Minor (in reality, her older sister, Domitia Lepida Major, is more commonly known historically as "Domitia", whereas D.L. Minor is more commonly known historically as "Lepida")

Thumbnail sketch: Mother of Messalina; sister to Emperor Nero's father; granddaughter of Octavia and Marc Antony; mother-in-law of Claudius.

Risk factors: An inability to control or face down her rebellious, wicked daughter.

Portrayed by: Moira Redmond

Whom you may also remember from: "The Avengers", "Danger Man", "A Shot in the Dark".

Full name: Tiberius Claudius Caesar Britannicus

Thumbnail sketch: Son of Claudius and Messalina; brother of Octavia the Younger; stepbrother of Nero; stepson of Agrippinilla.

Risk factors: Although there has been doubt spread about his paternity, there's not enough doubt about it to dispel Agrippinilla's focus on getting him out of the way of her son's chances to inherit the Imperial throne.

Portrayed by: Graham Seed

Whom you may also remember from: "The Archers" (radio), "Brideshead Revisited".

Full name: Julia Agrippina, or Agrippina Minor, or Agrippina the Younger

Thumbnail sketch: Wife (Claudius), mother (Nero), and sister (Caligula) of Emperors; daughter of Germanicus and Agrippina.

Risk factors: Intense love / hate relationship with her son.

Portrayed by: Barbara Young

Whom you may also remember from: "Coronation Street", the Lord Peter Wimsey series, "The Perfect Spy". (Of note - Miss Young is the widow of Jack Pulman, screenwriter of "I, Claudius".)

Full name: Nero Claudius Drusus Germanicus (original name: Lucius Domitius Ahenobarbus)

Thumbnail sketch: Fifth Emperor of Rome, ruled 13 years. Son of Agrippinilla and Gnaeus Domitius Ahenobarbus. Nephew of Caligula and Drusilla; grandson of Germanicus and Agrippina. Husband of Octavia the Younger and later of Poppaea Sabina.

Risk factors: Unstable, egomaniacal, and a mama's boy in the worst way.

Portrayed by: Christopher Biggins

Whom you may also remember from: "The Rocky Horror Picture Show" (the portly Transylvanian!), "Porridge".

Full name: Marcus Antonius Pallas

Thumbnail sketch: Greek freedman of Antonia; secretary to Claudius and Nero.

Risk factors: A freed Greek taking sides in the Imperial power struggle is not much safer than Imperial family members who do.

Portrayed by: Bernard Hepton

Whom you may also remember from: "The Six Wives of Henry VIII", "Elizabeth R", "Tinker, Tailor, Soldier, Spy", "Smiley's People", "Secret Army", "Colditz".

Full name: Tiberius Claudius Narcissus

Thumbnail sketch: Roman freedman and head of civil service under Emperor Claudius.

Risk factors: "Those ambitious nieces breaking up that ol' gang of mine..."

Portrayed by: John Cater

Whom you may also remember from: "Captain Kronos - Vampire Hunter", "The Duchess of Duke Street", "The Avengers", "Z Cars", "Down to Earth", "The Bill".