Histiaeus (Ancient Greek: Ἱστιαῖος, died 493 BC), the son of Lysagoras, was the tyrant of Miletus in the late 6th century BC.
Histiaeus owed his status as tyrant of Miletus to Darius I, king of Persia, who had subjugated Miletus and the other Ionian states in Asia Minor.
According to Herodotus, Histiaeus, along with the other tyrants under Darius' rule, took part in the Persian expedition against the Scythians, and were put in charge of defending the bridge that Darius' troops had placed across the Danube River. The Scythians attempted to persuade Histiaeus and the others to abandon the bridge; one faction, led by Miltiades of Athens, at that time tyrant of the Chersonese, wanted to follow the Scythians' advice. However, Histiaeus argued that they should stay, as they owed their positions as tyrants to Darius and would surely be overthrown if he were killed.
Instead, according to Herodotus, Histiaeus suggested that they pretend to follow the Scythian plan. So Histiaeus was sent as an ambassador to the Scythians to tell them that the tyrants would accept the Scythian plan, while the rest of the tyrants acted as if they were demolishing the bridge. Histiaeus persuaded the Scythians to look for the Persian forces.
Herodotus writes that while the Scythians were away, the Persians returned to the Danube and Histiaeus organized the ships to successfully ferry them across the river.
During the expedition, Histiaeus' troops had started building a settlement at Myrcinus (site of the later Amphipolis) on the Strymon River. After returning with Darius to Sardis, Darius asked Histiaeus what he wanted in return for his service. Histiaeus responded that he wanted to be given control over Myrcinus, to which Darius agreed.
However, the Persian commander Megabazus suspected Histiaeus' interest in the strategically important area, which controlled key roads from Persian controlled territory into Europe, as well as known sources of silver and timber. Nevertheless, Darius considered Histiaeus to be loyal, and asked him to come back to Susa with him as a friend and advisor. Histiaeus' nephew and son-in-law Aristagoras was left in control of Miletus.