From Franz Lidz, writing in the New York Times:

The fourth of the 12 Caesars, Caligula — officially, Gaius Julius Caesar Germanicus — was a capricious, combustible first-century populist remembered, perhaps unfairly, as the empire’s most tyrannical ruler. As reported by Suetonius, the Michael Wolff of ancient Rome, he never forgot a slight, slept only a few hours a night and married several times, lastly to a woman named Milonia.

The rest of the essay is worth your time.