Adak, formerly Adak Station, is a city located on Adak Island, in the Aleutians West Census Area, Alaska, United States. At the 2020 census, the population was 171, down from 326 in 2010. It is the westernmost municipality in the United States and the southernmost city in Alaska. The city is the former location of the Naval Air Facility Adak, NAVFAC Adak.

Adak Island or Father Island is an island near the western extent of the Andreanof Islands group of the Aleutian Islands in Alaska. Alaska's southernmost city, Adak, is located on the island. The island has a land area of 274.59 square miles (711.18 km2), measuring 33.9 miles (54.5 km) long and 22 miles (35 km) wide, making it the 25th largest island in the United States.