Admiral Sir William Donough O'Brien, KCB, DSC (13 November 1916 – 19 February 2016) was a senior officer in the Royal Navy who served as Commander-in-Chief of the Western Fleet from 1970 to 1971.

[3] In the early 1960s, O'Brien served as Director of Naval Plans at the Ministry of Defence under Lord Louis Mountbatten.

[1] In retirement, O'Brien became Chairman of the King George's Fund for Sailors.

[6] He became Chairman of the Kennet and Avon Canal and, after its re-opening by Queen Elizabeth II in 1990, he retired from this post.

[8] In 1943, O'Brien married Rita Micallef: they went on to have one son and two daughters.