Hyperbolus (Ancient Greek: Ὑπέρβολoς, Hypérbolos) was an Athenian politician active during the first half of the Peloponnesian war, coming to particular prominence after the death of Cleon.
Like Cleon, he counts as a demagogue, one who exercised power solely through speech in the assembly. Unlike Cleon, Hyperbolos did not have a noble background, appearing to be one of the first Athenian political leaders lacking aristocratic origins. It appears that like other such leaders he was wealthy. He is referred to by Aristophanes in the play Peace as having been a lampmaker previous to being a political figure.
Hyperbolus is universally reviled in the sources, even more so than his predecessor: both are associated with an alleged decline in Athenian political culture leading to the loss of the war with Sparta. Thucydides 8.73 is particularly vicious. In attacks on him with comedy he is represented as being of slavish and foreign background, both of which are improbable.
Sometime in the years 417-415 BC he was ostracised, perhaps the last person to be subject to the practice. Accounts of this ostracism by Plutarch describe a complex struggle with Nicias and Alcibiades, where Hyperbolos tried to bring about the ostracism of one of this pair but they combined their influence to induce the people to expel Hyperbolos instead. The validity of Plutarch's take on these events, however, is hard to gauge. Hyperbolus went to live on the island of Samos where he was murdered in 411 BC by oligarchic revolutionaries around the time of the coup of the 400 that for several months suppressed the democracy at Athens.
（Ὑπέρβολος). An Athenian demagogue in the Peloponnesian War, of servile origin. In order to get rid of either Nicias or Alcibiades, Hyperbolus called for the exercise of the ostracism. But the parties endangered combined to defeat him, and the vote of exile fell on Hyperbolus himself-an application of that dignified punishment by which it was thought to have been so debased that the use of it was never recurred to. Some years afterwards he was murdered by the oligarchs at Samos, B.C. 411 (Thuc.viii. 74).