The Renown class consisted of two battlecruisers built during the First World War for the Royal Navy. They were originally laid down as improved versions of the Revenge-class battleships, but their construction was suspended on the outbreak of war on the grounds they would not be ready in a timely manner. Admiral Lord Fisher, upon becoming First Sea Lord, gained approval to restart their construction as battlecruisers that could be built and enter service quickly. The Director of Naval Construction (DNC), Eustace Tennyson-D'Eyncourt, quickly produced an entirely new design to meet Admiral Lord Fisher's requirements and the builders agreed to deliver the ships in 15 months. They did not quite meet that ambitious goal, but they were delivered a few months after the Battle of Jutland in 1916. They were the world's fastest capital ships upon their commissioning.

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.