HMS Alacrity was a Cruizer-class brig-sloop built by William Rowe at Newcastle and launched in 1806. She served in the Baltic and was at the capture of Copenhagen in 1807. She captured a large privateer before herself falling victim to a French man-of-war in 1811 in an action in which her captain failed to distinguish himself. She then served in the French navy until she was broken up in 1822.