HMS Rattler was a 9-gun steam screw sloop of the Royal Navy, and one of the first British warships to be completed with screw propulsion. She was originally ordered as a paddle wheel 4-gun steam vessel (Steam Vessel Second Class – SV2) from Sheerness Dockyard on 12 March 1841. She was reordered on 24 February 1842 as a propeller type 9-gun (867-ton BM type) sloop from HM Royal Dockyard, Sheerness, as a new vessel. William Symonds had redesigned the ship as a screw propeller driven vessel.