Deioces,Diako, Deyaco, Diyako or Deiokes (Greek Δηιόκης) was the first king of the Medes according to Herodotus. In the late 8th century BC there was a Daiukku or Dayukku who was a Mannaean provincial governor. Perhaps Herodotus uses the name in error.
Read more about Deioces: Deioces in Herodotus, Daiukku in Assyrian Inscriptions, Cultural References