Full name: Gaius Julius Caesar Augustus Germanicus

Thumbnail sketch: Third Emperor of Rome, reigned under four years. Son of Germanicus and Agrippina; brother of Drusilla, Agrippinilla, Lesbia, Nero, and Drusus; husband of Caesonia; father of Julia Drusilla; nephew of Claudius.

Risk factors: The man is insane - there's only so long anyone is going to put up with him.

Portrayed by: John Hurt

Whom you may also remember from: "Alien", "Elephant Man", "Midnight Express", "1984", "Harry Potter and the Sorcerer's Stone", "The Lord of the Rings" 1978 animated movie as the voice of Aragorn.

Full name: Milonia Caesonia

Thumbnail sketch: Former courtesan and Caligula's Empress; mother of Julia Drusilla.

Risk factors: Married to an unpopular Emperor.

Portrayed by: Freda Dowie

Whom you may also remember from: "The Brontes of Haworth", various British television programs.

Full name: Julia Drusilla (the Elder)

Thumbnail sketch: Daughter of Germanicus and Agrippina; sister of Caligula, Agrippinilla, Nero, Drusus, and Lesbia.

Risk factors: Incest; playing up dangerous and blasphemous ideas to her brother.

Portrayed by: Beth Morris

Whom you may also remember from: "Crucible of Terror", "Son of Dracula", "Belonging".

Full name: Tiberius Gemellus (called "Gemellus" because he was one of twins, his brother Germanicus Gemellus having died in infancy)

Thumbnail sketch: Son of Castor and Livilla; brother of Helen; grandson of Tiberius; adopted son of Caligula; co-successor with Caligula to the Imperial throne.

Risk factors: Errr...co-successor with Caligula to the Imperial throne.

Portrayed by: Douglas Melbourne

Full name: Marcus Vinicius

Thumbnail sketch: A Roman consul; brother-in-law of Caligula through marriage to Caligula's sister Julia Livilla (called "Lesbia" by Robert Graves due to her birthplace, this character does not appear in the TV series "I, Claudius").

Risk factors: Emperor Caligula loathes his banished, treacherous tramp of a sister...who is Vinicius' wife.

Portrayed by: Norman Eshley

Whom you may also remember from: "Man About the House", "The Outsider", "The Bill".

Full name: Quintus Naevius Sutorius Macro

Thumbnail sketch: Prefect of the Praetorian Guard under two Emperors.

Risk factors: A willingness to ignore the backlash of treachery by those he assisted.

Portrayed by: John Rhys-Davies

Whom you may also remember from: "Raiders of the Lost Ark", "Shogun", "Sliders", "The Lord of the Rings" films.

Full name: Cassius Chaerea

Thumbnail sketch: Prefect of the Praetorian Guard; former centurion under Germanicus.

Risk factors: An intolerance for Imperial rule and personal mockery.

Portrayed by: Sam Dastor

Whom you may also remember from: "Space: 1999", "The Life and Death of Peter Sellers".