Mogami (最上) was the lead ship in the four-vessel Mogami class of heavy cruisers in the Imperial Japanese Navy. She was named after the Mogami River in Tōhoku region of Japan. The Mogami-class ships were constructed as "light cruisers" with five triple 155-millimetre (6.1 in) dual purpose guns. They were exceptionally large for light cruisers, and the barbettes for the main battery were designed for quick refitting with twin 8-inch (203 mm) guns. In 1937 all four ships were "converted" to heavy cruisers in this fashion. Mogami served in numerous combat engagements in World War II, until she was sunk at the Battle of Leyte Gulf in October 1944.

The Mogami class (最上型) was a ship class of four cruisers built for the Imperial Japanese Navy (IJN) during the 1930s. They were initially classified as light cruisers under the weight and armament restrictions of the London Naval Treaty. After Japan abrogated that agreement, all four ships were rearmed with larger guns and reclassified as heavy cruisers. All participated in World War II and were sunk.