The Admiral-class battlecruisers were to have been a class of four British Royal Navy battlecruisers built near the end of World War I. Their design began as an improved version of the Queen Elizabeth-class battleships, but it was recast as a battlecruiser after Admiral John Jellicoe, commander of the Grand Fleet, pointed out that there was no real need for more battleships, but that a number of German battlecruisers had been laid down that were superior to the bulk of the Grand Fleet's battlecruisers and the design was revised to counter these. The class was to have consisted of HMS Hood, Anson, Howe, and Rodney — all names of famous admirals — but the other three ships were suspended as the material and labour required to complete them was needed for higher-priority merchantmen and escort vessels. Their designs were updated to incorporate the lessons from the Battle of Jutland, but the Admiralty eventually decided that it was better to begin again with a clean-slate design so they were cancelled in 1919. No more battlecruisers would be built due to the arms limitations agreements of the interbellum.

The battlecruiser was a type of capital ship of the first half of the 20th century. These were similar in displacement, armament and cost to battleships, but differed in form and balance of attributes. Battlecruisers typically had thinner armour and a somewhat lighter main gun battery than contemporary battleships, installed on a longer hull with much higher engine power in order to attain greater speeds. The first battlecruisers were designed in the United Kingdom, as a development of the armoured cruiser, at the same time as the dreadnought succeeded the pre-dreadnought battleship. The goal of the design was to outrun any ship with similar armament, and chase down any ship with lesser armament; they were intended to hunt down slower, older armoured cruisers and destroy them with heavy gunfire while avoiding combat with the more powerful but slower battleships. However, as more and more battlecruisers were built, they were increasingly used alongside the better-protected battleships.