Robert Walpole, 1st Earl of Orford, KG, KB, PC (26 August 1676 - 18 March 1745), known before 1742 as Sir Robert Walpole, was a British statesman who is generally regarded as having been the first Prime Minister of Great Britain. This position had no official recognition in law, but Walpole is nevertheless acknowledged as having held the de facto office due to the extent of his influence in the Cabinet. However, the term "Prime Minister" was never used officially at this time.

Walpole, a Whig, served during the reigns of George I and George II. His tenure is normally dated from 1721, when he obtained the post of First Lord of the Treasury; others date it from 1730, when, with the retirement of Lord Townshend, he became the sole and undisputed leader of the Cabinet. The "longer" version of the tenure is generally upheld by the contemporary press, most notably that of the opposition, who focused far more attention upon Walpole than his counterpart. Walpole continued to govern until he resigned in 1742, making his administration the longest in British history.