George Richard James Hennessy, 1st Baron Windlesham, OBE (23 March 1877 – 8 October 1953) was a British soldier and Conservative politician.

Hennessy, a Franco-Irish aristocrat, served in the First World War as a Major in the King's Royal Rifle Corps and on the Staff of the 8th Division.

Hennessy held the latter position also from September to November 1931 in the National Government of Ramsay MacDonald.

Marthe Hennessy eventually remarried in 1888 with James Sholto Douglas (1855–1891), youngest brother of the Marquess of Queensberry.

He died in October 1953, aged 76, and was succeeded in the baronetcy and barony by his eldest son, James Hennessy, a brigadier in the Grenadier Guards.