Charles Boswell's short story "Monsters of Monarchy", Terror Tales, May 1940 features Roman emperor Caligula (12 BCE-24 CE), one of the most notorious Roman emperors. Known for his incestuous relationship with his sisters, and for his cruelty and madness, which culminated in Caligula naming his horse Roman consul and declaring himself a god. Caligula's brief reign and life turn into a complex and fascinating story of a boy-emperor thoroughly unprepared for the throne, who, in the early years of the Roman Empire, tried to make Rome an absolute monarchy but failed. A spoiled and reckless ruler who, for his transgressions against the traditional order, was tarnished by his enemies, becoming a madman, a tyrant, a pervert—one of the worst Roman emperors.

Caligula was indeed one of the most notorious Roman emperors, known for his controversial reign and outrageous behavior. Born Gaius Julius Caesar Augustus Germanicus in 12 BCE, he became emperor in 37 CE at the age of 25. Initially, Caligula was seen as a promising, popular ruler, with an emphasis on restoring an image of Rome's first emperor, Augustus. However, his rule quickly devolved into a period of extravagance, cruelty, and unchecked power.

Caligula's reign was marked by a range of unconventional and controversial actions. He was known for indulging in lavish displays of wealth, engaging in sexual promiscuity, and displaying a lack of respect for Roman traditions and institutions. His relationship with his sisters was considered incestuous, and he was accused of engaging in debauched activities. Caligula also showed signs of megalomania, declaring himself a god and demanding worship.