Bardiya in Wikipedia
Bardiya (Greek: Smerdis) (Old Persian: 𐎲𐎼𐎮𐎡𐎹 Bardiya; Ancient Greek: Σμέρδις) (possibly died 522 BCE) was a son of Cyrus the Great and the younger brother of Cambyses II, both Persian kings. There are sharply divided views on his life, he may have ruled the Achaemenid Empire for a few months in 522 BCE, or he may have been impersonated by a magus called Gaumata. (Old Persian: 𐎥𐎢𐎶𐎠𐎫 Gaumāta)
Name and sources
The prince's name is listed variously in the historical sources. His Persian name is Bardiya. He is called Tonyoxarces (Sphendadates) by Ctesias, he is called Tanooxares by Xenophon, who takes the name from Ctesias , and he is called Mardos by Justin  and Aeschylus. In the prevalent Greek form of his name, Smerdis, the Persian name has been assimilated to the Greek (Asiatic) name Smerdis or Smerdies, a name which also occurs in the poems of Alcaeus and Anacreon.
In English-language histories he has traditionally usually been called Smerdis, but recent histories are tending to call him Bardiya.
The traditional view based on the majority of ancient sources e.g. Darius the Great's Behistun inscription, as well as Herodotus, Justin, and Ctesias, although there are minor differences between them.
Bardiya was the younger son of Cyrus the Great and (full or half) brother of Cambyses II. According to Ctesias, on his deathbed Cyrus appointed Bardiya as satrap (governor) of some of the far-eastern provinces. According to Darius the Great, Cambyses II, after becoming king of Persia but before setting out for Egypt, killed Bardiya and kept this secret. However according to Herodotus who gives two detailed stories, Bardiya went to Egypt with Cambyses and was there for some time but later Cambyses sent him back to Susa out of envy, because "Bardiya alone could draw the bow brought from the Ethiopian king." Herodotus then states that "Cambyses had a dream in which he saw his brother sitting on the royal throne. As a result of this dream Cambyses sent his trusted counselor Prexaspes from Egypt to Susa with the order to kill Smerdis" (i.e. Bardiya).
Bardiya's death was not known to the people, and so in the spring of 522 BCE a usurper pretended to be him and proclaimed himself king on a mountain near the Persian town of Paishiyauvada. Darius claimed that the real name of the usurper was Gaumata, a Magian priest from Media; this name has been preserved by Justin i. 9 (from Charon of Lampsacus?) but given to his brother Cambyses (called Patizeithes by Herodotus) who is said to have been the real promoter of the intrigue. According to Herodotus, the name of the Magian usurper was Oropastes, but according to Ctesias it was Sphendadates.
The despotic rule of Cambyses, coupled with his long absence in Egypt, contributed to the fact that "the whole people, Persians, Medes and all the other nations," acknowledged the usurper, especially as he granted a remission of taxes for three years.
Cambyses began to march against him, but died in the spring of 522 BCE in disputed circumstances. Before his death he confessed to the murder of his brother, and publicly explained the whole fraud, but this was not generally believed. Nobody had the courage to oppose the new king, who ruled for seven months over the whole empire. The new king transferred the seat of government to Media.
A number of Persian nobles discovered that their new ruler was an impostor, and a group of seven nobles formed a plot to kill him. They surprised him at a castle in Nisa, home of the Nisean horses, and stabbed him to death in September 522 BCE. One of the seven, Darius, was proclaimed as ruler shortly after.
Some modern historians dispute the traditional story. They believe that the person who ruled for a few months was the real son of Cyrus, and that the story of his impersonation by a magus was an invention of Darius to justify his seizure of the throne. According to M. Dandamaev, this view "must remain hypothetical". There are some implausibilities in the "official" story e.g. the impostor resembled the real Bardiya so closely that even his harem of wives did not spot the difference. Darius often accused rebels and opponents of being impostors (e.g. Nebuchadnezzar III) it could be straining credulity to say that they all were.
In the next year, another person claiming to be Bardiya, named Vahyazdāta (Old Persian: 𐎺𐏃𐎹𐏀𐎭𐎠𐎫) rose against Darius in eastern Persia and met with great success. But he was finally defeated, taken prisoner and executed  Perhaps he is identical with the King Maraphis "the Maraphian," name of a Persian tribe, who occurs as successor in the list of Persian kings given by Aeschylus.
The real Bardiya had only one daughter, called Parmys, who eventually married Darius the Great.
Some contracts dating from his reign have been found in Babylonia, where his name is spelt Barziya or Bardiya. Darius says that Bardiya destroyed some temples, which Darius later restored. Bardiya also took away the herds and houses of the people, which Darius corrected once he gained the throne.
The death of the false Bardiya was annually celebrated in Persia by a feast called "the killing of the magian," (Magiophani) at which no magian was allowed to show himself.
Bardiya in fiction
This episode is dealt with by Gore Vidal in his novel Creation. He takes the view that the person who ruled for a few months was the real Bardiya.