Memucan is one of the royal counselors (advisers) at the court of Persian King Ahasuerus.
When Queen Vashti refused the king’s order to appear and dance, Memucan told him that she wronged not only the king, but also all of the husbands of Persia, whose wives may be encouraged by Vashti's actions to disobey. Memucan encouraged the king to divorce Vashti and find a new queen (Esther 1:14; 1:16; 1:21).
In the Sovereignty of God, this began a series of events which resulted in the orphan Esther replacing Vashti as queen, resulting in the salvation of the exiled Jews from mass genocide at the revengeful insistence of the king’s vizier Haman. Furthermore, Esther’s elder relative Mordecai (her adoptive father) replaced Haman as a vizier (viceroy) of highest position in the Persian empire.