The Acasta class (in September 1913 re-designated the K class) was a class of twenty destroyers built for the Royal Navy under the Naval Programme of 1911 - 1912 that saw service during World War I. They were the last class of Royal Navy destroyers to have mixed names with no systematic theme (see naming conventions for destroyers of the Royal Navy for more information.) When the class was designated as "K", names beginning with that letter were allocated to the ships but never used. The class saw extensive wartime service and seven were lost, including four at the Battle of Jutland.