Lionel Frederic Ellis CVO CBE DSO MC (13 May 1885 – 19 October 1970) was a British Army officer and military historian, author of three volumes of the official History of the Second World War.
Between the two World Wars, he was General Secretary of the National Council of Social Service (1919–1937) and then Secretary of the National Fitness Council (1937–1939). In the 1950s he was an Associate Warden of Toynbee Hall.