Cyrus I (Old Persian: Kuruš) or Cyrus I of Anshan, was King of Anshan in Persia from to 580 BC or, according to others, from to 600 BC. He should not be confused with his famous grandson Cyrus the Great, also known as Cyrus II. His name in Modern Persian is کوروش, Kurosh, while in Greek he was called Κῦρος, Kȳros.

The Achaemenid Empire (; ), also called the , was an empire based in Western Asia, founded by Cyrus the Great, notable for including various civilizations and becoming the largest empire of ancient history, spanning at its maximum extent from the Balkans and Eastern Europe proper in the west, to the Indus Valley in the east. It is equally notable for its successful model of a centralised, bureaucratic administration (through satraps under a king), for building infrastructure such as a postal system and road systems and the use of an official language across its territories and a large professional army and civil services (inspiring similar systems in later empires). It is noted in Western history as the antagonist of the Greek city states during the Greco-Persian Wars and for the emancipation of the Jewish exiles in Babylon. The Mausoleum at Halicarnassus, one of the Seven Wonders of the Ancient World, was built in the empire as well.