The Vice-Chief of the Defence Staff (VCDS) is the deputy to the Chief of the Defence Staff, the professional head of the British Armed Forces. The position was titled Deputy Chief of the Defence Staff before 1964. From 1966 to 1978 the post was occupied by a 3 star officer. From 1978 onwards the post has been held by a 4 star officer.

The Chief of the Defence Staff (CDS) is the professional head of the British Armed Forces and the most senior uniformed military adviser to the Secretary of State for Defence and the Prime Minister of the United Kingdom. The chief of the defence staff is based at the Ministry of Defence and works alongside the Permanent Under-Secretary of State for Defence, the ministry's senior civil servant. The Chief of Defence is the highest ranking officer to currently serve in the armed forces.