Caligula
Thus the Roman historian Suetonius speaks of the Emperor Caligula: "During the day he secretly consulted with Capitoline Jupiter, now speaking in a low voice and listening, now shouting and not without adding offense".
In practice, the first citizen of Rome considered himself a god and spoke with the gods as an equal, a typical madman attitude.
Indeed, according to most historians, Caligula (12-41 AD) was schizophrenic.
All the oddities and oddities attributed to this emperor, would be none other than some of the most evident manifestations of the very serious mental pathology he suffered from, which caused him hallucinations, paranoia, disorders of personality and constant mood swings.
Probably the too many atrocities committed against those who happened, otherwise inexplicable, were due to madness.