Major-General Thomas Pelham-Clinton, 3rd Duke of Newcastle-under-Lyne (1 July 1752 – 18 May 1795),[1] known as Lord Thomas Pelham-Clinton until 1779 and as Earl of Lincoln from 1779 to 1794, was a British Army officer and politician who sat in the House of Commons between 1774 and 1794 when he succeeded to the peerage as Duke of Newcastle.

Born on 1 July and christened on 28 July 1752 at St Margaret's, Westminster,[2] Pelham-Clinton was the second but eldest surviving son of Henry Pelham-Clinton, 2nd Duke of Newcastle-under-Lyne,[1] and his wife Lady Catherine Pelham, daughter of Henry Pelham.

Pelham-Clinton also sat as Member of Parliament for Westminster from 1774 to 1780 and for East Retford from 1781 to 1794 and was Lord Lieutenant of Nottinghamshire from 1794 to 1795.

He died, at his country seat at Sunninghill in Berkshire, in May 1795, aged 42, from the effects of an emetic which he had taken for whooping cough, having held the dukedom for only a year.

The Duchess of Newcastle-under-Lyne later married General Sir Charles Gregan Craufurd and died in 1834.