The name given to the King of Persia in the book of Esther and in Ezra (4.5-7). He is normally thought to be King Xerxes I who reigned 486-465 BC. Ahasuerus is also listed in the book of Daniel (9.1) as the father of Darius the Mede. This Ahasuerus is thought to be Astyages (585-550 BC).