I, Claudius - Season 1 Episode 9

Tiberius summons Caligula and his cousin Gemellus to Capri, declaring them his joint successors. Soon afterwards Tiberius is smothered by Macro, on the orders of Caligula, and his death is hailed joyfully by the citizens of Rome, unaware that worse is to come. Caligula, clearly unstable, sinks into a coma and on recovering, in addition to having Gemellus executed for trying to poison him, declares that he is the god Zeus and marries his sister Drusilla, declaring her a deity also. When Drusilla falls pregnant by him he cuts open her belly and eats the unborn child to prevent him having greater powers than himself as Zeus once allegedly did. Antonia, sickened by his depravity, kills herself.