Leslie Haden Guest, 1st Baron Haden-Guest, MC (10 March 1877 – 20 August 1960) was a British author, journalist, doctor and Labour Party politician.
Haden-Guest was born in Oldham, Lancashire, England, the son of Catharine Anna (née Johnson) and Alexander Haden-Guest, a physician and surgeon of Manchester who was an active worker for the left. He was educated first at William Hulme's Grammar School, then studied medicine at Owens College, Manchester, and the London Hospital.
He served in the Royal Army Medical Corps in the Boer War, World War I, and World War II, winning a Military Cross. He was the founder of the Anglo-French Committee of the Red Cross and the Order of St. John. He was a member of the London County Council for Woolwich (East), 1919-22. He was a Labour Member of Parliament (MP) for Southwark North, 1923–27, and for Islington North, 1937–50, and founded the Labour Party Commonwealth Group. He was created a peer 2 February 1950 as Baron Haden-Guest, of Saling in the Count of Essex and was a Lord-in-Waiting to the King, February–October 1951, and thereafter an Assistant Opposition Whip in the House of Lords. In 1898, he married Edith, daughter of Max Low of London, by whom he had two sons, Stephen and Richard. He was divorced in 1909 and in 1910 he married Muriel Carmel, the daughter of Albert Goldsmid. They had two sons, David who was killed in the Spanish Civil War, Peter, and a daughter, Angela. His third marriage was in 1944 to Dr. Edith Edgar Macqueen, daughter of George Macqueen. He was the grandfather of actor Christopher Guest.
Haden-Guest converted to Judaism before his marriage to Muriel Goldsmid, his second wife. He "renounced Judaism" in 1924, describing himself subsequently as a "Konfessionslos". He was the first Jew to stand for Parliament as a Labour candidate.