Gilbert Richard Mitchison, Baron Mitchison CBE QC, otherwise known as Dick Mitchison ( 23 March 1894–14 February 1970), was a British Labour politician.

Born in Staines, Mitchison was educated at Eton College and New College, Oxford and became a barrister (called 1917) and King's Counsel. He served with the Queen's Bays in World War I, attaining the rank of Major and gaining the Croix de Guerre. He worked in the Ministry of Labour during World War II on the Beveridge man-power survey and led the Nuffield College social reconstruction survey.

Mitchison stood for Parliament without success in King's Norton at the 1931 and 1935 elections. He was the Labour Member of Parliament for Kettering between 1945 and 1964, beating the young incumbent, John Profumo, at the 1945 election. In Parliament, Mitchison sponsored the New Streets Act as a private member's bill. He was given a life peerage, created Baron Mitchison, of Carradale in the County of Argyllshire on 5 October 1964. He served on the executive of the Fabian Society.

He married the writer Naomi Haldane (daughter of John Scott Haldane and sister of J.B.S. Haldane) in Oxford 1916. They had six children; four sons; Geoffrey (1918–1927) Denis (born 1919) later a professor of bacteriology, Murdoch (born 1922), and Avrion (born 1928), both professors of zoology. Their daughters were Lois and Valentine, the latter of whom married the historian Mark Arnold-Forster. He died in Westminster aged 75.