Hipparchus was one of the sons of Pisistratus who became tyrant of Athens when Pisistratus died in 527 BC.
Hipparchus ruled jointly with his brother Hippias. While Hippias was responsible for the political and economic aspects of the tyranny, Hipparchus was a patron of the arts; it was Hipparchus who invited Simonides of Ceos to Athens.
In 514 BC Hipparchus was murdered by the Tyrannicides, Harmodius and Aristogeiton. This was apparently a personal dispute, according to Herodotus and Thucydides; Hipparchus had fallen in love with Harmodius, who was already the lover of Aristogeiton. When Harmodius rejected him, Hipparchus refused to allow Harmodius' sister to participate in a religious festival, insinuating that she was not a virgin. As a result, Harmodius and Aristogeiton assassinated him.
After the assassination, Hippias became a more bitter and cruel tyrant, and was overthrown a few years later.