The 1st King's Dragoon Guards was a cavalry regiment in the British Army. The regiment was raised by Sir John Lanier in 1685 as the 2nd Queen's Regiment of Horse, named in honour of Queen Mary, consort of King James II. It was renamed the 2nd King's Own Regiment of Horse in 1714 in honour of George I. The regiment attained the title 1st King's Dragoon Guards in 1751. The regiment served as horse cavalry until 1937 when it was mechanised with light tanks. The regiment became part of the Royal Armoured Corps in 1939. After service in the First World War and the Second World War, the regiment amalgamated with the 2nd Dragoon Guards in 1959 to form the 1st The Queen's Dragoon Guards.

There are 13 cavalry Regiments of the British Army each with its own unique cap badge, regimental traditions, and history. Of the currently nine regular cavalry regiments, two serve as armoured regiments, three as armoured cavalry regiments, three as light cavalry, and one as a mounted ceremonial regiment. There are also four yeomanry regiments of the Army Reserve, of these, three serve as light cavalry and one as an armoured regiment. Each yeomanry light cavalry unit has been paired with a regular unit of the same role, the armoured yeomanry unit is paired with the two regular armoured units. All except the Household Cavalry are part of the British Army's Royal Armoured Corps.