Smerdis

Smerdis was the son of Cyrus the Great and younger brother of Cambyses II. At Cyrus' death, he was appointed governor of the eastern provinces of the Persian empire. Cambyses was worried that there would be a revolt while he was campaigning in Egypt, so he conspired for Smerdis to be killed. However, Smerdis' death was not known to the public. While Cambyses was away, a Magus named Gaumata pretended to be Smerids and took power in 522 BCE. He was eventually killed by Darius I in Darius' coup.