USS Willapa (AVG-53/ACV-53/CVE-53) was a Bogue-class escort aircraft carrier (originally an auxiliary aircraft carrier) in the United States Navy, leased to the United Kingdom.

Willapa was laid down on 21 May 1943 at Seattle, Washington, by the Seattle-Tacoma Shipbuilding Corporation and reclassified CVE-53 on 10 June 1943. Launched on 8 November 1943, the ship was transferred under lend-lease to the Royal Navy on 5 February 1944 to be manned by a Canadian crew.

Renamed HMS Puncher (D79), the carrier served the Royal Canadian Navy except for Fleet Air Arm personnel in the Atlantic and Mediterranean for the duration of hostilities. Stationed with Home Fleet at Scapa Flow, Puncher initially served in a training role, but was re-tasked to strike and convoy air protection (CAP) after her sister ship, HMS Nabob was torpedoed off Norway in 1944. Also part of her squadron was the US escort carrier USS Shamrock Bay. Puncher also provided convoy air protection on the Murmansk/Arkhangelsk convoy route which she did six times. Strike operations included German occupied Norway against industrial and shipping targets such as the steel works at Narvik on the west coast of Norway.

Fleet Air Arm squadrons assigned to Puncher included Fairey Barracuda fighter/bombers, Fairey Firefly fighter/bombers, American-built Hellcat (Wildcat) fighters and Avenger torpedo bombers. The Barracuda was one of the largest carrier-borne aircraft in the Royal Navy Fleet Air Arm and required rocket assistance to take flight from the small flight deck.

The Admiralty had determined that, in the post-war world, Canada would have her own aircraft carriers. Both HMS Puncher and HMS Nabob were crewed by RCN crews to establish the knowledge base for the future carriers assigned to Canada, HMCS Warrior (ex HMS Warrior), HMCS Magnificent (ex HMS Magnificent) ('The Maggie'), and HMCS Bonaventure (ex HMS Powerful) ('The Bonnie').

Decommissioned on 16 February 1946 at Norfolk, Virginia, and returned to American custody on that day, the escort carrier was struck from the Navy Registry on 12 March 1946, having never seen active service with the United States Navy.

Initially sold to William B. St. John, of New York City, on 9 January 1947, the carrier was subsequently resold to a British firm on 4 February 1947 and converted for mercantile service. She later served successively as Muncaster Castle, Bardic and Ben Nevis until she was scrapped in Taiwan in 1973.