Ahasuerus [Ăhăsū ē'rŭs]—king or mighty man.

1. A Persian monarch, to whom accusations against the Jews were brought, bore this name (Ezra 4:6).
2. It was also the name of a Median king, father of Darius (Dan. 9:1).
3. A Persian king who became the husband of Esther (Esther 1:2, 19).

The Man Whose Sleeplessness Saved a Nation

Two years after Queen Vashti was deposed, Esther the Jewess, and the ward of Mordecai, became the wife of Ahasuerus, and queen in Vashti’s place. Two years after Esther’s enthronement, wicked Haman prevailed upon the king to order the destruction of all the Jews in his empire, but the plan backfired. The king had a sleepless night, and robbed of slumber called for records carefully preserved in the royal archives. Reading of the plot to end his life, and of how Mordecai had informed the king, Ahasuerus felt that Mordecai was worthy of honor and reward. That sleepless night resulted in Mordecai’s promotion to high office, the exposure of Haman’s dark and devilish plot, the preservation of the Jewish nation and the hanging of Haman and his sons on the gallows Haman had prepared for Mordecai.

A character study on Ahasuerus could be worked out on his sensuality, fickleness, lack of forethought, despotism and cruelty.