HMS Irresistible—the fourth British Royal Navy ship of the name—was a Formidable-class pre-dreadnought battleship. The Formidable-class ships were developments of earlier British battleships, featuring the same battery of four 12-inch (305 mm) guns—albeit more powerful 40-calibre versions—and top speed of 19 knots (35 km/h; 22 mph) of the preceding Canopus class, while adopting heavier armour protection. The ship was laid down in April 1898, was launched in December that year, and was completed in October 1901. Commissioned in 1902, she initially served with the Mediterranean Fleet until April 1908, when she was transferred to the Channel Fleet. Now outclassed with the emergence of the dreadnought class of ships, she entered service with the Home Fleet in 1911 following a refit. In 1912, she was assigned to the 5th Battle Squadron.

Following the outbreak of World War I, Irresistible, along with the squadron, was assigned to the Channel Fleet. After operations with the Dover Patrol, during which she bombarded German forces in northern France, she was assigned to the Dardanelles Campaign in February 1915. She took part in numerous unsuccessful attacks on the Ottoman forts guarding the Dardanelles in February and March. These operations included several raids by landing parties to destroy Ottoman coastal artillery batteries. On 18 March, she struck a naval mine that caused extensive flooding and disabled her engines. Without power, she began to drift into the range of Turkish guns, which laid down a withering fire. Attempts to tow her failed, so her surviving crew was evacuated and Irresistible was abandoned and eventually sank. Her crew suffered around 150 killed in the sinking.