Unalaska is a small city on Unalaska Island in the Aleutian Islands, off the coast of the U.S. state of Alaska. As of the 2000 census, the population of the city is 4,283. The port area is on neighboring Amaknak Island and is known as Dutch Harbor. Dutch Harbor is within the city limits of Unalaska and is connected to Unalaska by a bridge.

The Aleut or Unangan have lived on Unalaska Island for thousands of years.

The Russian fur trade reached Unalaska when Stepan Glotov and his crew arrived on August 1, 1759.

Unalaska was named after Unalaska Island. The name "Unalaska" is likely an Americanization of the Russian name "Ounalashka". The regional native corporation has adopted this moniker, and is known as the "Ounalashka Corporation". Dutch Harbor was so named by the Russians because they believed that a Dutch vessel was the first European ship to enter the harbor.