Admiral Sir Astley Cooper Key, GCB, FRS, ADC (18 January 1821 – 3 March 1888) was a Royal Navy officer.

He later commanded a specially-formed Baltic Fleet created in February 1878 to intimidate Russia from entering Constantinople during the closing stages of the Russo-Turkish War.

[7] Key took command of the second-rate HMS Sans Pareil on the East Indies and China Station in January 1856 and went ashore with the naval brigade to take part in the Battle of Canton in December 1857 during the Second Opium War.

[9] Promoted to rear admiral on 20 November 1866,[10] Key was made Director of Naval Ordnance and became an expert on muzzle-loading guns, this being recognised when he was elected a Fellow of the Royal Society on 4 June 1868.

[13] He became Commander-in-Chief of the North America and West Indies Station in December 1875 and was then asked to command a specially-formed Baltic Fleet created in February 1878 to intimidate Russia from entering Constantinople during the closing stages of the Russo-Turkish War.

[2] Having been made a member of the Privy Council on 11 August 1884,[16] he retired in June 1885 and died at his home, Laggan House, in Maidenhead on 3 March 1888.