(Ἰσαγόρας), an Athenian, son of Tisander. Herodotus says that his family was one of note: of its remote origin he professes himself ignorant, but adds that his kinsmen sacrificed to Carian Zeus. When Cleomenes I. of Sparta came to Athens, in B. C. 510, to drive out Hippias, he formed a connection of friendship and hospitality with Isagoras, who was suspected of conniving at an intrigue between his wife and the Spartan king. Not long after this we find Isagoras, the leader of the oligarchical party at Athens, in opposition to Cleisthenes, and, when he found the latter too strong for him, he applied to Cleomenes for aid. The attempt made by the Spartans in consequence to establish oligarchy at Athens was defeated; and when Cleomenes, eager for revenge, again invaded Attica, with the view of placing the chief power in the hands of Isagoras, his enterprise again came to nothing, through the defection of the Corinthians and Demaratus. (Hdt. 5.66, 70-72, 74, 75; Plut. de Herod. Malign. 23 ; Paus. 3.4, 6.8.) [CLEISTHENES; CLEOMENES; DEMARATUS.]