This is a list of monitors of the Royal Navy of the United Kingdom.

The Humber-class monitors were three river monitors under construction for the Brazilian Navy in Britain in 1913, all three were taken over by the Royal Navy shortly before the outbreak of the First World War and were commissioned as small monitors, seeing extensive service during the war.

The Abercrombie-class monitors came about when Bethlehem Steel in the United States, the contracted supplier of the main armament for the Greek battleship Salamis being built in Germany, instead offered to sell the four 14"/45 caliber gun twin gun turrets to the Royal Navy on 3 November 1914, the ships were laid down and launched within six months, seeing service throughout the war.

The Lord Clive-class monitors, sometimes referred to as the General Wolfe-class, were built to meet the need for more shore bombardment ships, using twin 12-inch (305 mm) gun turrets taken from decommissioned Majestic-class pre-dreadnought battleships. Three of the ships, HMS General Wolfe, Lord Clive and Prince Eugene, were converted to take the BL 18 inch Mk I naval gun that had originally been allocated to HMS Furious.

The Marshal Ney-class monitors were built to use the two modern 15-inch turrets made available by the redesign of Renown and Repulse as battlecruisers.

The Gorgon-class monitors were originally built as coastal defence ships for the Royal Norwegian Navy, but requisitioned for British use.

The M15-class monitors were fourteen ships ordered in March 1915, as part of the War Emergency Programme of ship construction, mounting 9.2 inch Mk VI gun turrets removed from the Edgar-class and the Mk X turrets held in stock for the Drake-class and Cressy-class cruisers.

The M29-class monitors were five ships ordered in March 1915, as part of the War Emergency Programme of ship construction.

The Erebus-class monitors were two ships mounting a single twin BL 15 inch Mk I naval gun turret. They saw active service in World War I off the Belgian coast, were placed in reserve between the wars then served in World War II, with Terror being lost in 1941 and Erebus surviving to be scrapped in 1946.

The Roberts-class monitors were two ships mounting a single twin BL 15 inch Mk I naval gun turret built during the Second World War, featuring shallow draught for operating inshore, broad beam to give stability and a high observation platform to observe fall of shot.

• List of monitors of the United States Navy

Wikimedia Commons has media related to Monitors of the United Kingdom.

• Colledge, J. J.; Warlow, Ben (2006) [1969]. Ships of the Royal Navy: The Complete Record of all Fighting Ships of the Royal Navy (Rev. ed.). London: Chatham Publishing. ISBN 978-1-86176-281-8.