Peniston Lamb, 1st Viscount Melbourne (29 January 1745 – 22 July 1828), known as Sir Peniston Lamb, 2nd Baronet, from 1768 to 1770, was a British politician and the father of Prime Minister William Lamb, 2nd Viscount Melbourne.
Lamb was the son of Sir Matthew Lamb, 1st Baronet, and his wife Charlotte (née Coke), and succeeded in the baronetcy on his father's death in 1768. The same year he was returned to Parliament for Ludgershall, a seat he held until 1784, and then represented Malmesbury from 1784 to 1790 and Newport, Isle of Wight from 1790 to 1793. In 1770 he was raised to the Peerage of Ireland as Lord Melbourne, Baron of Kilmore, in the County of Cavan, and in 1781 he was created Viscount Melbourne, of Kilmore in the County of Cavan, also in the Peerage of Ireland. In 1815 he was even further honoured when he was made Baron Melbourne, of Melbourne in the County of Derby, in the Peerage of the United Kingdom, which gave him an automatic seat in the House of Lords.
He inherited Melbourne Hall in Derbyshire, and in 1770 began, as Melbourne House, what is now The Albany in London.
Lord Melbourne married Elizabeth Milbanke (1751–1818), daughter of Sir Ralph Milbanke, 5th Baronet, in 1769. She was a young woman of great beauty, intelligence and strong character, who quickly came to dominate her husband completely, and steered them into the centre of polite society. The couple had six children, (though only the first-born son can be definitively attributed to Lord Melbourne due to his wife's many affairs) George is reputed to be the son of George IV; with William and Emily allegedly fathered by Lord Egremont.