HMS Shamrock was an S-class destroyer, which served with the Royal Navy in the twentieth century. Launched on 26 August 1918 just before the end of the First World War, the ship was commissioned into the Home Fleet. A year later, the destroyer was sent to the Baltic Sea during the Russian Civil War to support Latvia, arriving just at the cessation of that country's war of independence. The vessel was later sent to join the Local Defence Flotilla at Gibraltar. It was while serving there that the destroyer escorted the first Prime Minister of Republican Spain, Niceto Alcalá-Zamora, on an official visit to Spanish Morocco and helped evacuate civilians from Malaga at the start of the Spanish Civil War. Shamrock was retired soon after and sold to be broken up on 23 November 1936.

The S class was a class of 67 destroyers ordered for the Royal Navy in 1917 under the 11th and 12th Emergency War Programmes. They saw active service in the last months of the First World War and in the Russian and Irish Civil Wars during the early 1920s. Most were relegated to the reserve by the mid-1920s and subsequently scrapped under the terms of the London Naval Treaty. Eleven survivors saw much action during the Second World War.