Horace Walpole by Joshua Reynolds 1756
National Portrait Gallery, collection London .

Horace Walpole, 4th Earl of Orford (24 September 1717 – 2 March 1797), more commonly known as Horace Walpole, was a politician, writer, architectural innovator and cousin of Lord Nelson.

He was born in London, the youngest son of British Prime Minister Robert Walpole. He was educated at Eton College and King's College, Cambridge. His homosexuality revealed itself early, and he is believed to have had affairs with the poet Thomas Gray, and with the 9th Earl of Lincoln (later the 2nd Duke of Newcastle-under-Lyne). Gray accompanied Walpole on the Grand Tour, but they quarrelled, and Walpole returned to England in 1741 and entered parliament. He was never politically ambitious, but remained an MP even after the death of his father in 1745 left him a man of independent means.

Following his father's politics, he was a devotee of King George II and Queen Caroline, siding with them against their son, Frederick, Prince of Wales, about whom Walpole wrote spitefully in his memoirs. Walpole's home, Strawberry Hill, near Twickenham, was a fanciful concoction of neo-Gothic which began a new architectural trend. From there, Walpole was a frequent visitor to Boyle Farm, Thames Ditton, to meet both the Boyle-Walsinghams and Lord Hertford. In 1764, he published his Gothic novel, The Castle of Otranto, setting a literary trend to go with the architecture. From 1762 on, he published his Anecdotes of Painting in England, based on George Vertue's manuscript notes. His memoirs of the Georgian social and political scene, though heavily biased, are a useful primary source for historians. In one of the numerous letters, from January 28, 1754, he coined the word serendipity which he said was derived from a "silly fairy tale" he had read, The Three Princes of Serendip. He also authored the often-quoted epigram, "Life is a comedy to those who think and a tragedy to those who feel."

His father was created Earl of Orford in 1742. Horace's elder brother, the 2nd Earl of Orford (c.1701–1751), passed the title on to his son, the 3rd Earl of Orford (1730–1791). When the 3rd Earl died unmarried, Horace Walpole became the 4th Earl of Orford. When Horace Walpole died in 1797 the title became extinct.

The Orford Walpoles were not related to the popular Twentieth Century novelist, Hugh Walpole (1884–1941).

Formal styles from birth to death

• Mr. Horace Walpole (1717-1741)
• Mr. Horace Walpole, MP (1741-1742)
• The Hon. Horace Walpole, MP (1742-1768)
• The Hon. Horace Walpole (1768-1791)
• The Rt. Hon. The Earl of Orford (1791-1797)