Brownlow Bertie, 5th Duke of Ancaster and Kesteven

Brownlow Bertie, 5th Duke of Ancaster (1 May 1729 in Lindsey House – 8 February 1809 in Grimsthorpe), styled Lord Brownlow Bertie until 1779, was a British peer. He was the son of Peregrine Bertie, 2nd Duke of Ancaster and Kesteven and Jane Brownlow, and the younger brother of Peregrine Bertie, 3rd Duke of Ancaster and Kesteven, and uncle of Robert Bertie, 4th Duke of Ancaster and Kesteven and Priscilla Bertie, 21st Baroness Willoughby de Eresby. He was baptized in London in the Church of St Giles in the Fields, Holborn.

Bertie was Member of Parliament for Lincolnshire from 1761 to 1779, became Lord Lieutenant of Lincolnshire on 12 February 1779, and was invested as Privy Counsellor on the same day. On his nephew's death on 8 July 1779, he succeeded him as 5th and last Duke of Ancaster and Kesteven and Marquess of Lindsey and as 8th Earl of Lindsey.

Ancaster married twice. His first wife, whom he married on 11 November 1762 in Cork Street in London, was Harriot Pitt (22 June 1745 – 23 April 1763). His second wife, whom he married on 2 January 1769 in St James's, was Mary Anne Layard (5 March 1733 – 13 January 1804).

His first marriage remained childless, while with his second wife he had one daughter:

The dukedom and the marquessate became extinct on his own death, while the earldom passed to his kinsman Albemarle Bertie. The Duke of Ancaster's funeral took place on 17 February 1809 at Swinstead.