Admiral Sir Benjamin John Key, is a senior Royal Navy officer. He has served as First Sea Lord since November 2021. He has commanded HM Ships Sandown, Iron Duke and Lancaster, and deployed on operations to Kosovo and Iraq. He was appointed Fleet Commander in 2016, and the Chief of Joint Operations in 2019.

The First Sea Lord and Chief of the Naval Staff (1SL/CNS) is a statutory position in the British Armed Forces usually held by a four star admiral. As the highest-ranking officer to serve in the Royal Navy, the chief is the principal military advisor on matters pertaining to the navy and a deputy to the Secretary of State for Defence. In a separate capacity, the CNS is a member of the Chiefs of Staff Committee and, thereby, a military advisor to the National Security Council, the prime minister and the monarch. The First Sea Lord is typically the highest-ranking officer on active duty of the Royal Navy unless the Chief of the Defence Staff is a naval officer. Admiral Ben Key was appointed First Sea Lord in November 2021.