HMS Dreadnought was a Royal Navy battleship, the design of which revolutionised naval power. The ship's entry into service in 1906 represented such an advance in naval technology that her name came to be associated with an entire generation of battleships, the dreadnoughts, as well as the class of ships named after her. Likewise, the generation of ships she made obsolete became known as pre-dreadnoughts. Admiral Sir John "Jacky" Fisher, First Sea Lord of the Board of Admiralty, is credited as the father of Dreadnought. Shortly after he assumed office in 1904, he ordered design studies for a battleship armed solely with 12 in (305 mm) guns and a speed of 21 knots. He convened a Committee on Designs to evaluate the alternative designs and to assist in the detailed design work.

The Royal Navy (RN) is the naval warfare force of the United Kingdom, British Overseas Territories and Crown Dependencies, and a component of His Majesty's Naval Service. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against France. The modern Royal Navy traces its origins to the early 16th century; the oldest of the UK's armed services, it is consequently known as the Senior Service.