Admiral of the Fleet Sir Francis William Austen, was a Royal Navy officer and an elder brother of the novelist Jane Austen. As commanding officer of the sloop HMS Peterel, he captured some 40 ships, was present at the capture of a French squadron, and led an operation when the French brig Ligurienne was captured and two others were driven ashore off Marseille during the French Revolutionary Wars.

Admiral of the Fleet is a five-star naval officer rank and the highest rank of the Royal Navy, formally established in 1688. The five-star NATO rank code is OF-10, equivalent to a field marshal in the British Army or a Marshal of the Royal Air Force. Apart from honorary appointments, no new admirals of the fleet have been named since 1995, and no honorary appointments have been made since 2014.