William Lamb, 2nd Viscount Melbourne (15 March 1779 – 24 November 1848), in some sources called Henry William Lamb, was a British Whig statesman who served as Home Secretary (1830–1834) and Prime Minister (1834 and 1835–1841). He is best known for being prime minister in Queen Victoria's early years and coaching her in the ways of politics, acting almost as her private secretary. Historians have concluded that Melbourne does not rank highly as a Prime Minister, for there were no great foreign wars or domestic issues to handle, he lacked major achievements, he enunciated no grand principles, and he was involved in several political scandals in the early years of Victoria's reign.
Melbourne was Prime Minister on two occasions. The first ended when he was dismissed by King William IV in 1834, the last British prime minister to be dismissed by a monarch. Six months later he was re-appointed and served for six years.