The Emerald class or E class was a class of two light cruisers built for the Royal Navy. Following the Cavendish class, three ships of a new class were ordered in March 1918, towards the end of World War I, designed to emphasise high speed at the cost of other qualities, for use against rumoured new high-speed German cruisers – like the Brummer class – and particularly minelayers, in the North Sea. The third ship was cancelled in November 1918.

The Danae or D class consisted of eight light cruisers built for the Royal Navy at the end of World War I which also saw service in World War II.