HMS Britannia was a King Edward VII-class pre-dreadnought battleship of the Royal Navy. She was named after Britannia, the Latin name of Great Britain under Roman rule. The ship was built by Portsmouth Dockyard between 1904 and 1906. Armed with a battery of four 12-inch (305 mm) and four 9.2 in (234 mm) guns, she and her sister ships marked a significant advance in offensive power compared to earlier British battleship designs that did not carry the 9.2 in guns.

The King Edward VII class was a class of eight pre-dreadnought battleships launched by the Royal Navy between 1903 and 1905. The class comprised King Edward VII, the lead ship, Commonwealth, Hindustan, Britannia, Dominion, New Zealand, Africa, and Hibernia. They marked the first major development of the basic pre-dreadnought type that had been developed with the Majestic type of the mid-1890s, all of which had been designed by the Director of Naval Construction, William Henry White, with the primary innovation being the adoption of a heavy secondary battery of four 9.2-inch (234 mm) guns to supplement the standard main battery of four 12 in (305 mm) guns. The King Edward VIIs were among the last pre-dreadnoughts built for the Royal Navy before the construction and launch of the revolutionary battleship HMS Dreadnought in 1906, which immediately rendered them obsolescent.