"His physical features were almost perfect, the only exception being his head, which was rather long and out of proportion. For this reason almost all his portraits show him wearing a helmet, since the artists apparently did not wish to taunt him with this deformity."
Plutarch, Pericles (III.2)
Critics of Pericles and the comic poets tended to be less solicitous and called him "squill-head," after the large elongated bulb of the squill, or sea-onion, which grows on the coast of the Mediterranean. Although the epithet usually is assumed to refer to the shape of his head, it is more likely that Pericles was ridiculed for being bald. Or the story may have derived simply to explain that his bust displays a helmet.
"Cresilas did...the Olympian Pericles, a figure worthy of its title; indeed it is a marvellous thing about the art of sculpture that it has added celebrity to men already celebrated."
Pliny, Natural History (XXXIV.74)
The bronze portrait statue of Pericles by Cresilas is probably the same one seen by Pausanius (I.25.1, I.28.2) on the Acropolis. The idealized head survives in several Roman herm-and-bust copies, two of which, in the Vatican (above) and British Museum (below), are inscribed with his name. Made soon after Pericles died in the Athenian plague of 429 BC, he wears the Corinthian helmet that signifies his position as strategos, commander of the army in the Peloponnesian War (431-404 BC), a war between Sparta and Athens and their allies that, after twenty-seven years of intermittent fighting, left Sparta in command of a devastated Greece.
References: The Rise and Fall of Athens: Nine Greek Lives by Plutarch (1960) translated by Ian Scott-Kilvert (Penguin Classics); Pausanias: Description of Greece (1918) translated by W. H. S. Jones (Loeb Classical Library); Pliny: Natural History (1938-) translated by H. Rackham et al. (Loeb Classical Library).