HMS Preventer (Z265) was a net laying ship for the Royal Navy during the Second World War acquired from the United States Navy in September 1944 via Lend-Lease.

The ship was laid down as Seagrape (YN-90), a net tender of the Ailanthus class, on 20 May 1943 at the American Car and Foundry Co. in Wilmington, Delaware.

After delivery to the U.S. Navy on 30 September, she was transferred to the United Kingdom under Lend-Lease the same day and commissioned into the Royal Navy as HMS Preventer (Z265).

Upon completion of wartime duty with the United Kingdom, she was returned to the U.S. Navy on 10 January 1946.

Struck from the Naval Vessel Register in March 1946, she was transferred to the United States Maritime Commission on 1 April 1947.