The Three Great Kings of the Persian Empire

The three great kings of the Persian Empire were Cyrus the Great, Darius the Great, and Xerxes the Great. His empire was amongst the first to exist as a world empire (Achaemenids). In 539 B.C.E he annexed the Chaldaean Empire "ithout spilling a drop of blood". He arrested Nabonidus and claimed various titles, such as King of the Four Corners of the World.
Darius the Great came into power in September of 522 B.C.E. He organized the empire by dividing the empire into regions and hiring satraps to govern those areas. Darius died shortly after the Battle of Marathon and his son Xerxes I took the throne.
Xerxes the Great came to power immediately after the death of Darius the Great. He spent time fighting in Greece, he went back to the Empire and finished all the construction work that hadn't been finished. He was murdered in 465 B.C.E by a man named  Artabanus.