Birker Fell, also known as Birker Moor, is an upland wilderness area in the western portion of the Lake District National Park, in Cumbria, England. Rather than being formed of one single high peak, the fell is a broad, undulating area, approximately 6 km square, with numerous crags and prominences scattered across its area. The highest point of the fell is at Green Crag (489m, grid reference SD200983). The fell is bordered by the Duddon Valley to the south-east, Ulpha Fell to the south-west, Harter Fell to the north-east, and Eskdale to the north-west. One small hamlet, Birkerthwaite (grid reference SD179982), lies in a shallow valley near the centre of the fell, but other than this the only human habitations are scattered hill farms. A road crosses the fell between Eskdale Green and Ulpha, in the Duddon Valley.