Gearhart Mountain Wilderness is a wilderness area located within the Fremont–Winema National Forest in Lake County and Klamath County in south-central Oregon. This area was established in 1943 as a Wild Area and designated as wilderness with the Wilderness Act of 1964. In 1984, an additional 4,144 acres (1,677 ha) were added for a total of 22,823 acres (9,236 ha). The wilderness is entirely within the Bly Ranger District. Gearhart Mountain was named for James P. Gearhart and William H. Gearhart, two brothers who raised and traded cattle in the area from about 1873 to 1882.