The Commander Islands, Komandorski Islands, or Komandorskie Islands are a series of islands in the Russian Far East, a part of the Aleutian Islands, located about 175 km (109 mi) east of the Kamchatka Peninsula in the Bering Sea. Treeless and sparsely populated, the islands consist of Bering Island, Medny Island and fifteen islets and rocks. The largest of the latter are Tufted Puffin Rock (Kamen Toporkov or Ostrov Toporkov), 15 ha, and Kamen Ariy, which are between 3 km (1.9 mi) and 13 km (8.1 mi) west of the only settlement, Nikolskoye. Administratively, the Commanders compose the Aleutsky District of the Kamchatka Krai in Russia.

The Aleutian Islands —also called the Aleut Islands, Aleutic Islands, or, before 1867, the Catherine Archipelago—are a chain of 14 main, larger volcanic islands and 55 smaller ones. Most of the Aleutian Islands belong to the U.S. state of Alaska, with the archipelago encompassing the Aleutians West Census Area and the Aleutians East Borough. The Commander Islands, located further to the west, belong to the Russian federal subject of Kamchatka Krai, of the Russian Far East. The islands form part of the Aleutian Arc of the Northern Pacific Ocean, and occupy a land area of 6,821 sq mi (17,666 km2) that extends westward roughly 1,200 mi (1,900 km) from the Alaskan Peninsula mainland, in the direction of the Kamchatka Peninsula; the archipelago acts as a border between the Bering Sea to the north and the Pacific Ocean to the south. Crossing longitude 180°, at which point east and west longitude end, the archipelago contains both the westernmost and easternmost parts of the United States, by longitude. The westernmost U.S. island, in real terms, however, is Attu Island, west of which runs the International Date Line. While nearly all of the archipelago is part of Alaska at the extreme western end, the small, geologically-related Commander Islands belong to Russia.