Fisher Caldera, also known as Mount Fisher and Fisher Volcano, is a large volcanic caldera, measuring about by , located on Unimak Island in the Aleutian Islands of Alaska. Formed by the destructive eruption of an andesitic stratovolcano about 9,100 years ago, it contains three crater lakes, one wide and two others about wide. Small peaks rising and are also present in the caldera. Fisher Caldera is located just from the Mount Westdahl volcano.
The largest volcanic eruption on Earth during the Holocene Epoch (the last 11,700 years) occurred at Fisher Caldera in 8700 BCE.