Gaius Caesar Caligula was a Roman emperor who ruled from 37 AD to 41 AD. He is known for his tyrannical rule and erratic behavior, which included extravagant spending, cruelty, and megalomania. Caligula's reign was marked by political instability and widespread fear among the Roman people. He was assassinated by members of the Praetorian Guard, leading to a period of uncertainty and power struggles within the Roman Empire.