Smith's Bible Dictionary

Vashti (beautiful), the "queen" of Ahasuerus, who, for refusing to show herself to the king’s guests at the royal banquet, when sent for by the king, was repudiated and deposed. (Esther 1:1) ... (B.C. 483.) Many attempts have been made to identify her with historical personages; but it is far more probable that she was only one of the inferior wives, dignified with the title of queen, whose name has utterly disappeared from history.