William IV was King of the United Kingdom of Great Britain and Ireland and King of Hanover from 26 June 1830 until his death in 1837. The third son of George III, William succeeded his elder brother George IV, becoming the last king and penultimate monarch of the United Kingdom's House of Hanover. Born: August 21, 1765 Died: June 20, 1837 In office: June 26, 1830 – June 20, 1837 Wiki link