Hipparchus (Ancient Greek: Ἵππαρχος, romanized:  Hípparkhos; died 514 BC) was a member of the ruling class of Athens and one of the sons of Pisistratus.

The word tyrant literally means "one who takes power by force", as opposed to a ruler who inherited a monarchy or was chosen in some way.

Hipparchus then invited Harmodius' sister to participate in the Panathenaic Festival as kanephoros only to publicly disqualify her on the grounds that she was not a virgin.

[2][3] After the assassination of his brother, Hippias is said to have become a bitter and cruel tyrant, and was overthrown a few years later in 510 BC by the Spartan king Cleomenes I.

Some modern scholars generally ascribe the tradition that Hipparchus was himself a cruel tyrant to the cult of Harmodius and Aristogeiton established after the downfall of the tyranny; however, others have advanced the theory that the cult of the tyrannicides was a propaganda coup of the early democratic government to obscure Spartan involvement in the regime change.