Earl of Durham is a title in the Peerage of the United Kingdom. It was created in 1833 for the Whig politician and colonial official John Lambton, 1st Baron Durham. Known as "Radical Jack", he played a leading role in the passing of the Great Reform Act of 1832. As Governor General of British North America, he was the author of the famous Report on the Affairs of British North America, known in Canada as the Durham Report. He had already been created Baron Durham, of the City of Durham and of Lambton Castle in the County Palatine of Durham, in 1828. He was created Viscount Lambton at the same time that he was raised to the earldom. These titles are also in the Peerage of the United Kingdom.

John George Lambton, 1st Earl of Durham,, also known as "Radical Jack" and commonly referred to in Canadian history texts simply as Lord Durham, was a British Whig statesman, colonial administrator, Governor General and high commissioner of British North America. A leading reformer, Durham played a major role in the passage of the Reform Bill of 1832. He later served as ambassador to Russia. He was a founding member and chairman of the New Zealand Company that played a key role in the colonisation of New Zealand. George Woodcock says that he was, "Proud, wayward, immensely rich, with romantic good looks and an explosive temper." He was one of those "natural rebels who turn their rebellious energies to constructive purposes. Both at home and abroad he became a powerful exponent of the early nineteenth-century liberal spirit."