The fourth HMS Rupert (K561) was a British Captain-class frigate of the Royal Navy in commission during World War II.

The ship was laid down as the unnamed U.S. Navy destroyer escort DE-96 by Bethlehem-Hingham Shipyard, Inc., in Hingham, Massachusetts, on 25 August 1943 and launched on 31 October 1943.

[2] Commissioned into service in the Royal Navy as the frigate HMS Rupert (K561) on 24 December 1943 simultaneously with her transfer, the ship served on patrol and escort duty.

On 30 March 1945, she joined the British frigate HMS Conn (K509) in a depth charge attack which sank the German submarine U-965 north of Scotland in position 58°19′00″N 005°31′00″W / 58.31667°N 5.51667°W / 58.31667; -5.51667 (U-965 sunk).

[1][2] On 27 April 1945, the German submarine U-1105 detected three British frigates in the North Atlantic Ocean 25 nautical miles (46 km) west of County Mayo, Ireland, and fired two G7es – known to the Allies as "GNAT" – torpedoes at them.