), one of the seven Persian noblemen who conspired against the Magi in B. C. 521.
He commanded for Xerxes on the seacoast of Asia Minor, and entertained Sperthias and Bulis when they were on their way to Susa to deliver themselves up to the king as a compensation for the Persian ambassadors slain at Sparta. (Hdt. 3.70
; Strab. xi. p.531
.) Herodotus mentions another Hydarnes (7.83, 211) as the commander of the select band of Persians called the Immortals in Xerxes' invasion of Greece.
It is doubtful whether the Hydarnes mentioned in Hdt. 7.66
is to be identified with either of the above.