Otanes (Old Persian: Utāna, Ancient Greek: Ὀτάνης), son of Sisamnes, was an Achaemenid judge and later Satrap of Ionia during the reign of Darius the Great, c. 500 BC.

He later took on military responsibilities under Darius, that led him to have an important role in suppressing the Ionian Revolt.

Otanes' father Sisamnes had been one of the royal judges, and Cambyses had cut his throat and flayed off all his skin because he had been bribed to give an unjust judgment.Otanes succeeded Megabazus as the governor/supreme commander of the united forces of the peoples of the Aegean (5.26.1), and subjugated Byzantium and other cities during the Ionian revolt (5.123.1, 5.116.1).

He captured Byzantium, Calchedon, Antandrus in the Troad, and Lamponium, and with ships he had taken from the Lesbians, he took Lemnos and Imbros, both of which were still inhabited by Pelasgians.

[1]According to Herodotus, this Otanes also married one of Darius' daughters (5.116.1): "Daurises, Hymaees, and Otanes, all of them Persian generals and married to daughters of Darius, pursued those Ionians who had marched to Sardis, and drove them to their ships.