The protagonist of the series, as well as the narrator. His life is essentially one tragedy after another. Played by Derek Jacobi
- A God Am I: Subverted and played straight. He technically is worshiped as one, but he sure as hell doesn't want it.
- Awesomeness by Analysis: Used his historical knowledge to win battles and retrieve the last Eagle, and learns to play Caligula like a lyre after Caligula's descent into insanity.
- Classical Anti-Hero: He really doesn't want to be a Hero. He certainly doesn't look like one, either. Tough: he always steps up to the plate and does whatever it takes to make things work.
- Cloudcuckoolander: Although it's mostly an act.
- Crouching Moron, Hidden Badass: Claudius practically personifies this trope.
- Guile Hero: To some extent. While he's not The Chessmaster, during Caligula's reign his Obfuscating Stupidity alone wouldn't be enough to save him, thanks to Caligula's cask-strength insanity and psychotic urges. Several times he saves his own life, as well as the lives of others around him, by manipulating Caligula with not-inconsiderable skill. He's also a skilled administrator, and manages a long and (mostly) successful reign as Emperor largely due to extreme competence in the face of being loved by almost nobody.
- Historical Hero Upgrade: Claudius and his desire to restore the Roman Republic, which is also somewhat unhistorical, since at that time there was no distinction made between the Republican and Imperial eras.
- Lonely at the Top: The isolation involved with being a member of such an important family is one of his major problems. Becoming Emperor certainly doesn't help it, either.
- Not So Above It All: A darker version of this trope: Claudius thinks he can remain separate from the murderous schemes absorbing his family. Unfortunately, when Claudius himself comes to power, he finds he must get his own hands dirty in order to survive.
- Obfuscating Disability
- Obfuscating Stupidity: Something like 80% of the reason that he survives for as long as he does.
- Properly Paranoid: Claudius is convinced his (last) wife is trying to poison him. Oh, wait. She is.
- Reluctant Ruler: He even tried to hide behind curtains to avoid it. The Praetorian Guard as a united body weren't about to let him get away with that...
- Speech Impediment: Though it improves as he gets older.
- Ugly Guy, Hot Wife: With Messalina. It ends badly.
- The Unfavourite: His mother, Antonia, was always disgusted by him in comparison to Germanicus.
- You Should Have Died Instead: Claudius' mother lobs this at him after the death of her more accomplished son, Germanicus.
- Zero-Approval Gambit: It's all part of the plan to get Rome thoroughly sick of autocratic rule.
Augustus's scheming wife, who is willing to do ANYTHING to ensure that her son gets the throne.
- Black Widow: She poisons Augustus by smearing poison on the figs that he picks himself.
- The Chessmaster: Oh, wow: she's a scarily effective bitch on wheels and master plotter, this one.
- Deadpan Snarker: When you can make Augustus want to wince just imagining what you're going to say before you actually say it, you know you're good.
- Even Evil Has Standards: As horrible as Livia was, even she was disgusted to learn that Caligula had murdered his own father. And she felt genuinely bad about murdering Augustus.
- Evil Matriarch: Given her tendencies to have her own family killed or banished if it means Tiberius will become emperor.
- A God Am I: Feels it's the only way to avoid eternal damnation.
- God Save Us from the Queen!: She'll do anything to make sure her lad gets to wear lots of purple. Anything.
- Historical Villain Upgrade: In all likelihood, the real Livia was not a scheming mastermind and never poisoned anyone.
- I Did What I Had to Do: Livia ruthlessly manipulates and kills family members and anyone else close to them to ensure her son becomes emperor and Rome does not return to being a Republic, convinced this is the only way for the city to remain great.
- The Extremist Was Right: Cladius has a great deal of personal hatred for Livia, but Deifies her anyway after being Emperor and learning how much work she did to make everything work.
- Ignored Epiphany: Admits she was a terrible criminal and person, but decides it was all worth it in the end.
- I Was Quite a Looker: Livilla mentions that she was said to be the most beautiful woman in the world.
- Manipulative Bitch: She plays Augustus like a fiddle.
- Master Poisoner: To the point where a fellow Mistress of the art gets a chance to really panic at how much she knows. Over lunch.
- My Beloved Smother: To Tiberius.
- Offing the Offspring
Claudius's mother, and one of the few "moral" people in Rome. Though how sane she is is rather questionable.
Claudius's brother, and one of the few people to treat him with any compassion at all. Is eventually offed by his son.
Claudius's insane nephew, and the third emperor of Rome. Played by John Hurt
- 0% Approval Rating
- Blond Guys Are Evil: As opposed to his father's Hair of Gold, Heart of Gold. The resemblance is part of why the senators trust him initially, much to everyone's eventual horror.
- Brother-Sister Incest: With Drusilla. "And you know how I love my sisters..."
- The Caligula: Well Duh.
- Creepy Child: He becomes partially responsibly for the murder of his father when he was just hitting puberty.
- Creepy Crossdresser: Performed before three utterly baffled men who assumed they were to be murdered.
- Enfant Terrible: Is already a murderer before he even hit puberty.
- Evil Nephew: Inspired the page and Caligula's actions even provide the page quote.
- A God Am I: In the more usual sense.
- Hair-Trigger Temper: After going insane. Celebrate the anniversary of the battle of Actium, and he throws a fit. Don't celebrate it, and he throws a fit. Please don't mention the fact that his grandfather was a commoner.
- I'm a Humanitarian: He cuts out and eats Drusilla's unborn child, fearing it will become more powerful than he.
- Insane Equals Violent: Subverted. His violent/psychopathic tendencies are explicitly shown NOT to follow from his psychotic delusions: he's a killer from childhood, but doesn't go mad until after he becomes Emperor years later. Livia and other murderous characters are described as "mad" by other characters, but are not shown as irrational - even Nero, explicitly called "as mad as... Caligula", is clearly nothing of the kind.
- It Amused Me: Caligula has some shades of this - he does things like set up the young, beautiful Messalina with unattractive Claudius because he thinks it's funny.
- Large Ham: He is played by John Hurt, by the way.
- Manipulative Bastard: Right up until he loses all touch with reality as Emperor.
- Spanner in the Works: In more ways than one. Livia consents to him being made Tiberius' heir because of a complex scheme that will result in her elevation to godhood (and thus avoid eternal damnation). When Livia is on her deathbed, Caligula gleefully turns on her, and later comes very close to destroying the empire Livia worked so hard to build.
- Villainous Incest: With his sister. He also kisses his stone-faced great-grandmother on the lips.
Claudius's uncle, and the second emperor. Played by George Baker.
- 0% Approval Rating
- Berserk Button: Mention Agrippina's name around Tiberius and he'll want to murder everything in sight.
- Colonel Badass: A very capable general.
- Dirty Old Man: Have you heard about his "nymphs" at Capri?
- Happily Married: Until Livia ruins it.
- Kick the Dog: The scene where a woman he's raped is driven to commit suicide in front of her husband and guests is pretty much there to show us he's much less pitiable since he became emperor.
- King on His Deathbed
- Lonely at the Top: His ghost admits as much to Claudius.
- Momma's Boy: A very tragic example of one.
- Offstage Villainy: Most of his horrific actions take place elsewhere and we find out second-hand. This can be somewhat jarring as we only see him as a very sad and pathetic figure on screen.
- Pet the Dog: Tiberius's scenes with Drusus are there to establish that he did in fact have some redeeming points in his youth.
- Reluctant Ruler: Tiberius was fairly reluctant about the role his mother planned for him, too. The power went to his head pretty quickly, though.
- Sergeant Rock: "They say your drills are bloodless battles, and your battles are bloody drills." Tiberius, however, is fair, even sleeping without a tent if his troops couldn't have one.
- Sketchy Successor: Played with. As a heir to Augustus he is for the most part portrayed as a depraved tyrant; yet Claudius acknowledges that he was competent at governing the empire and that the majority of the population had little reason to complain during his reign, with only the minority suffering from his repressions. However, the trope is played completely straight during the last years of his reign, when he just stops caring about the administration of the empire whatsoever.
- Stuffed In The Fridge
- Training from Hell: His take on army training.
- Vorpal Pillow: Tiberius's fate.
- With Great Power Comes Great Insanity
- Yandere: After divorcing Vipsania, he becomes this. Subverted in that he was forced into a divorce, and his love of his wife was one of his few redeeming qualities.