Esther, originally Hadassah, is the eponymous heroine of the Book of Esther in the Hebrew Bible. According to the biblical narrative, which is set in the Achaemenid Empire, the Persian king Ahasuerus falls in love with Esther and marries her. His grand vizier Haman is offended by Esther's cousin and guardian Mordecai because of his refusal to bow before him; bowing in front of another person was a prominent gesture of respect in Persian society, but deemed unacceptable by Mordecai, who believes that a Jew should only express submissiveness to God. Consequently, Haman plots to have all of Persia's Jews killed, and eventually convinces Ahasuerus to permit him to do so. However, Esther foils the plan by revealing and decrying Haman's plans to Ahasuerus, who then has Haman executed and grants permission to the Jews to take up arms against their enemies; Esther is hailed for her courage and for working to save the Jewish nation from eradication.

The Book of Esther, also known in Hebrew as "the Scroll", is a book in the third section of the Hebrew Bible. It is one of the Five Scrolls in the Hebrew Bible and later became part of the Christian Old Testament. The book relates the story of a Jewish woman in Persia, born as Hadassah but known as Esther, who becomes queen of Persia and thwarts a genocide of her people.