After establishing the identity—agreed upon by the majority of scholars—between King Ahasuerus in the book of Esther and the Persian ruler known to the Greeks as Xerxes (both variants of the original Persian Khshayarsha), Mitchell First seeks extra-biblical evidence of the book’s other characters:
The Greek historians Herodotus and Ctesias refer to Xerxes’ wife as Amestris. Although some slight linguistic connection between the name Amestris and the name Vashti . . . seems possible, a stronger connection exists between the Greek Amestris and the Hebrew Esther.
The -is at the end [of Amestris] is just a Greek suffix added to turn the foreign name into a proper Greek [feminine noun]. The name . . . is based around the consonants m, s t, and r; the name as recorded in the Megillah is based around the consonants s, t, and r. Very likely, this is not coincidence; perhaps her Persian name was composed of the consonants m, s t, and r and the m was not preserved in the Hebrew. . . .
[Both] Herodotus and Ctesias depict Amestris as cruel. It should be noted, however, that many scholars today doubt the stories told by the Greek historians about their enemies, the Persians; those concerning royal Persian women are particularly suspect.