Mount Shishaldin () is a moderately active volcano on Unimak Island in the Aleutian Islands chain of Alaska. It is the highest mountain peak of the Aleutian Islands. The most symmetrical cone-shaped glacier-clad large mountain on Earth, the volcano's topographic contour lines are nearly perfect circles above . The lower north and south slopes are somewhat steeper than the lower eastern and western slopes. The volcano is the westernmost of three large stratovolcanoes along an east-west line in the eastern half of Unimak Island.