HMS Cossack (L-03/F-03/G-03) was a Tribal-class destroyer which became famous for the boarding of the German supply ship Altmark in Norwegian waters, and the associated rescue of sailors originally captured by the Admiral Graf Spee.

Cossack was laid down by the High Walker Yard of Vickers Armstrong at Newcastle-on-Tyne on 9 June 1936, launched on 8 June 1937 by Mrs. S. V. Goodall, commissioned on 7 June 1938 and completed on 14 June 1938.

Cossack's first major taste of warfare was on February 16 1940. This was the celebrated action in Jøssingfjord which resulted in the freeing of the Admiral Graf Spee prisoners.

Shortly afterwards Cossack participated in the Second Battle of Narvik (April 1940) and in the pursuit and destruction of Bismarck (in May 1941).

On 21 October 1941, Cossack was struck by one torpedo fired by the submarine U-563 as she escorted a convoy from Gibraltar to the United Kingdom. She was taken in tow by a tug from Gibraltar on 25 October but the weather worsened and the tow was slipped on 26 October. Cossack sank in the Atlantic west of Gibraltar on 27 October 1941. 159 of her crew were lost.

See HMS Cossack for other ships of this name.