The Pacific Ocean Theater was one of four major theaters during the Pacific War between 1942 and 1945. It takes its name from the major Allied command in the theater, known simply as "Pacific Ocean Areas". The Theater included most of the Pacific Ocean and its islands. It excluded the Philippines, Australia, the Netherlands East Indies, the Territory of New Guinea (including the Bismarck Archipelago) and the western part of the Solomon Islands (which were part of the Southwest Pacific Area). The Pacific Ocean Theater also excluded China and mainland South East Asia.

Forces from the Empire of Japan mostly fought units from the United States in the Pacific Ocean Theater. Army, navy and air units from New Zealand were also involved. The United Kingdom, Australia, Canada, Fiji and other countries also contributed ships, planes and/or soldiers.