USS Alacrity (PG-87) was an Action-class patrol boat acquired by the United States Navy for the task of patrolling American coastal waters during World War II. The gunboat was constructed in Collingwood, Ontario, Canada by the Collingwood Shipyard, Ltd. as the British Flower-class corvette HMS Cornel (K-278). It was transferred to the U. S. Navy on 6 January 1942; launched on 4 September 1942; and commissioned at Collingwood on 10 December 1942, Lieutenant H. M. Godsey, USNR, in command. It was the second ship to be named Alacrity by the U.S. Navy.