John Frederick Sackville, 3rd Duke of Dorset, KG was the only son of Lord John Philip Sackville, second son of Lionel Sackville, 1st Duke of Dorset. His mother was the former Lady Frances Leveson-Gower. He succeeded to the dukedom in 1769 on the death of his uncle, Charles Sackville, 2nd Duke of Dorset. He was the British Ambassador to France from 1784 and returned to England in August 1789 following the escalation of the French Revolution.

Lionel Cranfield Sackville, 1st Duke of Dorset was an English peer and politician who served as Lord President of the Council from 1745 to 1751. He also twice served as Lord Lieutenant of Ireland from 1730 to 1737 and again from 1750 to 1755.