Mardale Ill Bell is a fell in the English Lake District, rising to the south west of Haweswater Reservoir.

South-east of the summit a rough narrowing ridge drops to Nan Bield Pass at 2,100 feet (640 m), before rising again over rocky steps to Harter Fell.

Nan Bield was the ancient trading route between Kentmere and the now drowned village of Mardale Green, submerged by the raising of Haweswater in the 1940s.

North-west from Mardale Ill Bell the grassy ridge crosses a wet depression and then expands into a wide plateau, triangular in plan.

From the road end Nan Bield pass can be used, or the impressive scenery of Piot Crag can be attained from the shore of either Blea or Small Water.