X is King Xerxes, of Persia nation. The cause of his death? Assassination. Portia: Scholars believe that King Ashasuerus of the book of Esther is Xerxes the Great. Xerxes the Great, along with the xylophone and the x-ray fish, is a favorite subject of alphabet books, as words that begin with "x" are uncommon in English. Conveniently for me, scholars believe that the King Ashasuerus mentioned in the book of Esther is Xerxes the Great. Like Roman Emperor Tiberius, Xerxes' assassination is not recorded in the Bible, but is attested to in other ancient sources. Thomas: Long before I knew the story of Esther, I knew of Xerxes from Edward Lear's Nonsense Alphabet Number 2: " X was once a great king Xerxes, Xerxy, Perxy, Turxy, Xerxy, Linxy, lurxy, Great King Xerxes!" Both Xerxes and his assassin are based on illustrations in Lear's books.