Mount Fillmore is a named summit in the Plumas National Forest of Sierra County, California, in the northern Sierra Nevada. It stands about 8 miles northeast of La Porte and 12 miles north of Downieville, placing it within a remote forested mountain landscape. The mountain was named for a naval officer. Although few additional details are given, its significance lies in its place among the identified peaks of this part of the Sierra and in the preserved record of its name and location within the region.