William Cavendish, 5th Duke of Devonshire, KG (14 December 1748 – 29 July 1811), was a British nobleman, aristocrat, and politician.

At the age of about twenty, Devonshire toured Italy with William Fitzherbert which is where they commissioned the pair of portraits by Pompeo Batoni.

By his first wife, he had one son (William Cavendish, 6th Duke of Devonshire, sometimes called "The Bachelor Duke", who succeeded him and who died unmarried in 1858), and two daughters: Lady Georgiana "Little G" Cavendish, later the Countess of Carlisle (wife of George Howard, 6th Earl of Carlisle), and Lady Harriet "Harryo" Cavendish, later the Countess Granville (wife of Lord Granville Leveson-Gower, who would be created 1st Earl Granville).

By his second wife, Lady Elizabeth Foster, he had no legitimate issue, but the couple had two illegitimate children born before their marriage.

He used the profits from his copper mines to transform the town into a replica of Bath, including the Crescent Hotel and an octagonal set of stables, which later became the Devonshire Dome.