The Fremont National Forest was a United States National Forest located in western Lake and eastern Klamath counties in Oregon. In 2002, the forest was merged with the Winema National Forest to form the Fremont–Winema National Forest.
Founded in 1908, the Fremont National Forest was originally protected as the Goose Lake Forest Reserve in 1906. The name was soon changed to Fremont National Forest, named after John C. Frémont, who explored the area for the United States Army Corps of Engineers in 1843. It absorbed part of Paulina National Forest on July 19, 1915. In 2002, it was administratively combined with the Winema National Forest as the Fremont–Winema National Forests.