Plato's first name

Diogenes Laertius, in "Lives and Doctrines of Ancient Philosophers" volume 3: Life of Plato, says that Plato's real name was Aristocles, son of Ariston, of the deme of Colytus (a deme is like a neighborhood). He wrote this in the 3rd century, AD.

He appears to be quoting Alexander of Miletus, who lived in the first century BC.

Plato means "Broad", and Diogenes says that some say it was given to him by a gym teacher because he was big-boned, others that it was a reference to the breadth of his work.