The Household Cavalry Composite Regiment was a temporary, wartime-only, cavalry regiment of the British Army consisting of personnel drawn from the 1st Life Guards, 2nd Life Guards and Royal Horse Guards. It was active in 1882 for service in the Anglo-Egyptian War, in 1889-1900 during the Second Boer War and from August to November, 1914, during the opening months of the Great War.
When the British Expeditionary Force was mobilised, it had a war establishment of seventeen cavalry regiments - five cavalry brigades of three regiments each, and two regiments which would be broken up to serve as reconnaissance squadrons, one per division. The peacetime establishment in the United Kingdom was nineteen cavalry regiments - sixteen line regiments, and the three regiments of the Household Cavalry.
The sixteen regular regiments were earmarked for overseas service, whilst the seventeenth regiment was to be provided by a composite regiment formed with a squadron from each of the three Household Cavalry regiments - the 1st Life Guards, the 2nd Life Guards, and the Royal Horse Guards - and assigned a mobilisation role in 4th Cavalry Brigade.
The regiment deployed to France with the Expeditionary Force, and saw action through 1914. It was broken up in November, with the squadrons returning to their parent regiments; these had since been deployed to the Continent, landing in October.
From 1916 to 1918, an infantry battalion, the Household Battalion, was formed from reserve regiments of the 1st Life Guards, 2nd Life Guards and Royal Horse Guards.
During World War II, in 1939, the Life Guards and Royal Horse Guards formed the Household Cavalry Composite Regiment and the Household Cavalry Training Regiment. In 1940, these regiments were reorganised into the 1st and 2nd Household Cavalry Regiments, which were disbanded in 1945 and the personnel returned to their original units.