Henry Dundas, 1st Viscount Melville, PC, FRSE, styled as Lord Melville from 1802, was the trusted lieutenant of British prime minister William Pitt and the most powerful politician in Scotland in the late 18th century.

William Pitt was a British statesman, the youngest and last prime minister of Great Britain from 1783 until the Acts of Union 1800, and then first prime minister of the United Kingdom from January 1801. He left office in March 1801, but served as prime minister again from 1804 until his death in 1806. He was also Chancellor of the Exchequer for all of his time as prime minister. He is known as "Pitt the Younger" to distinguish him from his father, William Pitt, 1st Earl of Chatham, who had previously served as prime minister and is referred to as "William Pitt the Elder".