|Satrap of Caria|
|Born||4th century BCE.|
Halicarnassus, Caria, Persian Empire
(Dynasts of Caria)
Idrieus, or Hidrieos (Ancient Greek: Ἱδριεύς, romanized: Hidrieús; died 344 BC) was a ruler of Caria under the Achaemenid Empire, nominally a Satrap, who enjoyed the status of king or dynast by virtue of the powerful position his predecessors of the House of Hecatomnus (the Hecatomnids) created when they succeeded the assassinated Persian Satrap Tissaphernes in the Carian satrapy.
Shortly after his accession he was required by the Persian king, Artaxerxes III Ochus, to provide arms and troops for the capture of Cyprus, a request with which he readily complied. He equipped a fleet of 40 triremes and assembled an army of 8000 mercenary troops. These were despatched for use against Cyprus under the command of Evagoras and the Athenian general Phocion. This is the only recorded event preserved from his reign. However; it can be inferred from Isocrates that by 346 BC the friendly relations between Idrieus and the Persian king had not continued and there appears to have been open hostility between the two.
But the hostility of Persia did not interfere with Caria's prosperity, for in the same passage by Isocrates, Idrieus is described as one of the most wealthy and powerful of the princes of Asia and Demosthenes advises  that Idrieus had added the important islands of Chios, Cos, and Rhodes to his hereditary dominions.
That Idrieus was an active builder is attested in Halicarnassus, as it is he who must have finished the Mausoleum, the tomb of his brother Mausolus, begun by their sister, Mausolus' wife, and his own immediate predecessor, Artemisia II, which had been left unfinished at her death; and at Labraunda (alternatively Labranda Ancient Greek: Λάβρανδα), where, continuing the enrichment in the Hellenistic style undertaken there earlier by Mausolus, he restored the temple of Zeus, added the southern and eastern entrances, and built the 'Doric house'.
Hecatomnus had several children, all of whom would rule at some point following his death. After his eldest son Mausolus, his other children were Artemisia, Idrieus, Ada, and Pixodarus. The children of Hecatomnus practiced monogamous sibling marriage, with Mausolus marrying Artemisia and Idrieus marrying Ada.
This article incorporates text from a publication now in the public domain: Smith, William, ed. (1870). "Idrieus". Dictionary of Greek and Roman Biography and Mythology.