* DawsonCasting: Because the series takes place over nearly eighty years, this is both played straight and later inverted with many of the same characters. Just to name a few major examples:
** Creator/DerekJacobi, aged 38, played Claudius from the age of 19 to his death at 63.
** Siān Phillips, aged 43, played Livia from the age of 34 to her death at 86.
** George Baker, aged 45, played Tiberius from the age of 18 to his death at 77.
** Margaret Tyzack, also aged 45, played Antonia from the age of 27 to her death at 73.
** Some examples where this is purely played straight include Creator/JohnHurt (aged 36) as Caligula from the age of 17 to his death at 28, Christopher Biggins (aged 28) as 17-year-old Nero, and Graham Seed (aged 26) as ''13''-year-old Britannicus.
* HeyItsThatGuy:
** Claudius is [[Series/DoctorWho The Master!]]
*** Or, if you ''really'' want to be clever: "Hey! [[Theatre/{{Hamlet}} Claudius]] is playing Claudius!"
** Augustus is '''''BrianBlessed!!!'''''
** Livia is [[Film/{{Dune}} The Reverend Mother Gaius Helen Mohiam!]]
** Tiberius is Inspector Wexford.
** Caligula is [[Film/{{Alien}} Kane!]]
*** Caligula and Macro were definitely a couple at [[TheNakedCivilServant one point]].
** Aelius Sejanus is [[Series/StarTrekTheNextGeneration Captain Picard!]]
*** With Hair?!
** Macro is [[LordOfTheRings Gimli!]]
** Livilla is [[RockyHorrorPictureShow Magenta!]]
*** While Nero is another of the Transylvanians. Or, alternatively, [[{{Series/Porridge}} Lukewarm]].
** Martina the Poisoner is is [[{{Blackadder}} Nursie!]]
** Herod is [[Literature/BridgetJones Uncle Geoffrey!]]
** Julia is [[Series/MayToDecember Miss Flood!!]]
** When Claudius is hiding from the Praetorian Guard, he is found by [[Series/BoysFromTheBlackstuff Yosser]], whose sergeant is [[Film/AHardDaysNight Norm!]]
** Agrippina is [[Recap/DoctorWhoS25E3SilverNemesis Lady Peinforte]]!
** And pretty much every actor who turns up has appeared in at least one other BBC production. There's even a [[http://calapine.dreamwidth.org/459307.html Doctor Who/I, Claudius DRINKING GAME]].
** Castor is [[PiratesOfTheCaribbean Mr. Gibbs]], though [[IWasQuiteALooker you really wouldn't know it.]]
** Livia's slave in episode one is [[Series/AlloAllo Lieutenant Gruber]]!
** The British chieftain Caractacus in the final episode is [[Series/ToTheManorBorn Richard DeVere]]!
* {{Plagiarism}}: Not this work, but it turns out that Richard Condon plagiarized several passages from ''I, Claudius'' in ''TheManchurianCandidate''. This went unnoticed until a few years after Condon died.
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