Caligula is the play’s protagonist. While his name is noted as Caligula in the written text, most of the other characters refer to him in dialogue by his personal name, Caius. As a historical figure, Caligula was among the most notorious of the Roman emperors, rivaling or exceeding even the infamous Nero and Domitian in depravity. He reigned from 37 to 41 CE, a short period of rule between the longer reigns of Tiberius and Claudius. Camus’s portrayal of Caligula follows along historical lines. However, he interprets Caligula’s behavior according to 20th-century nihilism or absurdism rather than the philosophical perspectives of the first century. In other words, Camus takes the story of a historical figure and reinterprets it to explore modern ideas.

The play presents Caligula as having been a good emperor until the death of his sister and mistress Drusilla, which triggers an epiphany about reality’s true nature. Convinced that nothing lasts and that death is the only certainty, Caligula comes to realize that everything else—the value of love, good and evil, right and wrong—are meaningless. Unless the impossible can be realized, the limits of reality bind human life into a system where nothing matters.