The emperor Commodus allegedly fed a man to the beasts simply for reading Suetonius’ Life of Caligula. This grim, yet oddly entertaining, anecdote is in all likelihood the product of someone’s creative imagination. But, though fictitious, it does serve a valuable purpose, illustrating as it does the powerful impact that Caligula’s malign reputation has had on later generations. It is, in fact, safe to say that, of all the emperors of ancient Rome, none, with the possible exception of Nero, surpasses Caligula’s reputation for infamy, and Nero had fourteen years to hone his image, against Caligula’s modest four. The quintessential mad despot, Caligula has inspired a stream of successful plays, films and television series. Yet while the public at large has always seemed to find him irresistible, until recently academic biographers tended to give him a wide berth. This is not altogether surprising. The loss of the relevant books of the most important ancient commentator on the early Roman Empire, the historian Tacitus, means that we have to rely for our information on markedly inferior sources, in particular the late historian Dio and the biographer Suetonius. Any possible bias on their part is not the main problem. Scattered references to Caligula made by Tacitus in the context of other emperors leave us in no doubt that his account must have been, if anything, more hostile than those that have survived, and it would almost certainly have been coloured by Tacitus’ own special brand of bias. A far more serious difficulty is that much of the material recorded in the surviving sources is anecdotal and trivial, often in the form of the emperor’s intentions rather than his actual deeds, and is at times presented with such little coherence that even a simple but reliable reconstruction of chronological events still largely eludes us. As a consequence, for a long time most surveys of Caligula’s life tended, with some minor exceptions, to avoid critical analysis and to limit themselves essentially to paraphrased selections of Suetonius and Dio.