Ruler of Persia from 486 to 465 BCE; called Ahasuerus in Ezra 4: 6. His defeat by the Greeks at the naval battle of Salamis in 480 BCE is described by the Greek historian Herodotus. There are problems about the biblical chronology, since the complaint against the returning Jews (Ezra 4: 6) must have been made just before 445 BCE. However, the problems may be easily solved by detaching 4: 6 from 4: 7, which belongs in the reign of a different ruler.
Ahasuerus (Xerxes I) is the Persian ruler in the book of Esther, but this book is more in the nature of legend than history. In Dan. 9: 1 Ahasuerus is said to be the father of Darius the Mede, though in fact he was the son of Darius the Great.