The genre of the book of Esther is Narrative History. Its author is anonymous however; some believe Mordecai, (Esther’s cousin and guardian), wrote it. It was written approximately 470 B.C. in Persia. Esther became queen in 479 B.C. The key personalities are Esther, Mordecai, King Ahasuerus (or Xerxes), and Haman.