ABOUT TWO DOZEN busts with this face are known, some for quite a while, Rubens bought one in Italy. The best one, unlike most others in bronze with inlaid eyes, was found 1754 in the garden of the Villa of the Papyri in Herculaneum and is now in the Museo Archeologico Nazionale in Naples.
In spite of the popularity of the bust we have no idea whose portrait it is. It was long thought to depict Seneca, but in 1813 a duble herma of Socrates and Seneca was found in Rome, with a very different face for Seneca. The bust was henceforth known as the Pseudo-Seneca.
Since then, there have been various theories, for example that the bust shows Lucius Calpurnius Piso Caesoninus, who is sometimes thought to have been the owner of the Villa of the Papyri. It would fit the shaggy looks Cicero made fun of in his speech in Pisonem, but is otherwise not all too plausible.
The common consensus is that the busts are all copies of a lost original from around 200 BC. It might show Hesiod, or Aristophanes, or someone else. We don’t know.