In the Book of Esther
According to Esther, she refused to obey the King's request that she "show off her beauty" in the banquet hall of the palace of "Shushan" (Susa), leading to concerns that, if unpunished, her actions would inspire other wives to disobey their husbands, and ultimately to the decision that she must not remain Queen. King Ahaseurus's command for the appearance of Queen Vashti is sometimes interpreted as an order to appear unclothed and/or dance for attendees. Though it was common in the culture for dancers to entertain the king's guests, this interpretation is inconsistent with Persian customs that "the queen, even more than the wives of other men, was secluded from the public gaze". In further dispute of this interpretation is the fact that the Biblical Old Testament, the most exhaustive collection of ancient Hebrew writings from the era of Esther, contains no instances of the Hebrew word "יֳפי" ("yopî"—transliterated, pron: "yof-ee", English: "beauty")describing Queen Vashti in the Biblical account of the story in any context associating it with nudity or indecency.
Although the Book of Esther states only that Vashti ceased to be Queen and was never again to come before the King, the king's advisors convinced the king that if word got around, wives would no longer obey their husbands.  Her refusal to obey her husband has helped to secure her status as a folk hero of the modern feminist movement as well as a villain because of her disobedience.
In the Midrash
According to the Midrash, Vashti was the great-granddaughter of King Nebuchadnezzar II of Babylon, the granddaughter of King Amel-Marduk and the daughter of King Belshazzar. Midrash also holds that she had a tail.
Identification in history
In the 19th and early 20th century, Bible commentators attempted to identify Vashti with Persian queens mentioned by the Greek historians. Upon the discovery of the equivalence of the names Ahasuerus and Xerxes, Bible commentators attempted to identify Ahasuerus with Xerxes I of Persia and Vashti with a wife named Amestris mentioned by Herodotus. Traditional sources, however, identify Ahasuerus with Artaxerxes II. Jacob Hoschander supporting the traditional identification suggested that Vashti may be identical to a wife of Artaxerxes mentioned by Plutarch, named Stateira.  These identifications are problematic however. Amestris remained in power well into the reign of her son Artaxerxes I and moreover the identification of Ahasuerus with Xerxes was rejected by later scholars. Similarly details of Stateira do not accord with Vashti as Stateira was an early wife murdered by Artaxerxes II's mother while the events of Purim occur late in his reign. (Artaxerxes II is said to have had 350 wives.)
Persian tradition recorded by Al-Tabari regards Vashti as a distinct historical figure.
Meaning of the name
The meaning of the name Vashti is uncertain. As a modern Persian name it is understood to mean "beauty" or "goodness". It may have originated from the reconstructed Old Persian *vaištī, related to the superlative adjective vahišta- "best, excellent" found in the Avesta, with the feminine termination -ī; hence "excellent woman, best of women".
Hoschander proposed that it originated as a shortening of an unattested vashtateira which he also proposed as the origin of the name "Stateira" .
Hitchcock' Bible Names Dictionary of the 19th century, attempting to interpret the name as Hebrew, suggested the meanings "that drinks" or "thread". Critics of the historicity of the book of Esther proposed that the name may have originated from a conjectured Elamite goddess whom they called "Mashti."
Vashti is one of a very few proper names in the Tanakh that begins with the letter waw, and by far the most prominently mentioned of them. Hebrew names that begin with waw are rare because of the etymological tendency for word-initial waw to become yodh (e.g. Hebrew יין yáyin "wine" < Proto-Semitic *wayn).
- The Machine Stops, The Oxford and Cambridge Review (November 1909)
- The Oxford Bible Commentary (edited by John Barton and John Muddiman, NY: Oxford University Press, 2001, pages 326-327, written by Carol Meyers)
- Asimov's Guide to the Bible, Random House, 1969