William IV was King of the United Kingdom from 1830 until his death in 1837. He was the third son of King George III and became king after the death of his brother, King George IV. Known as the "Sailor King," he had a naval career before ascending the throne and was popular for his down-to-earth personality. During his reign, William IV oversaw significant political changes, including the passage of the Reform Act of 1832, which expanded the electorate and reformed parliamentary representation. His reign also saw the abolition of slavery in the British Empire in 1833, marking a pivotal moment in British history.