Mikasa (三笠^?) is a pre-dreadnought battleship built for the Imperial Japanese Navy (IJN) in the late 1890s, and was the only ship of her class. Named after Mount Mikasa in Nara, Japan, the ship served as the flagship of Admiral Tōgō Heihachirō throughout the Russo-Japanese War of 1904–1905, including the Battle of Port Arthur on the second day of the war and the Battles of the Yellow Sea and Tsushima. Days after the end of the Russo-Japanese War, Mikasa's magazineaccidentally exploded and sank the ship. She was salvaged and her repairs took over two years to complete. Afterwards, the ship served as a coast-defence ship during World War I and supported Japanese forces during the Siberian Intervention in the Russian Civil War.

After 1922, Mikasa was decommissioned in accordance with the Washington Naval Treaty and preserved as a museum shipat Yokosuka. She was badly neglected during the post-World War II Occupation of Japan and required extensive refurbishing in the late 1950s. She is now fully restored as a museum ship and can be visited at Mikasa Park in Yokosuka.

Mikasa is the last remaining example of a pre-dreadnought battleship anywhere in the world.