Vashti Amestris - Nice Try.

The text in Esther does NOT say he "banished" her. In fact the gory details are omitted entirely: See Esther 1:19-21 -

If it please the king, let a royal edict go forth from before him, and let it be inscribed in the laws of Persia and Media, and let it not be revoked, that Vashti shall not come before King Ahasuerus, and let the king >>give her royal position<< to her peer who is better than she. :: And let the verdict of the king be heard throughout his entire kingdom, although it is great, and all the women shall give honor to their husbands, both great and small." :: And the matter pleased the king and the princes, and the king did according to the word of Memucan.

Also: Esther 2:1
After these events, when King Ahasuerus's fury subsided, he remembered Vashti and what she had done, and what had been decreed upon her.

Until relatively recently, kings almost never "banished" their wives. This could cause no end of embarrassment, AND political turmoil. Especially in cases, like these, where the queen herself was Royalty by birth. So "ex-queens" almost always ended up DEAD. And that is exactly what the commentaries say happened here. Had she merely been banished, then the verse of Esther 2:1 would not make any sense. He could just "unbanish" her. Being dead sort of prevented that.