Ladybower Reservoir is a large Y-shaped, artificial reservoir, the lowest of three in the Upper Derwent Valley in Derbyshire, England. The River Ashop flows into the reservoir from the west; the River Derwent flows south, initially through Howden Reservoir, then Derwent Reservoir, and finally through Ladybower Reservoir. The reservoir is owned by Severn Trent.

The Upper Derwent Valley is an area of the Peak District National Park in England. It largely lies in Derbyshire, but its north eastern area lies in Sheffield, South Yorkshire. Its most significant features are the Derwent Dams, Ladybower, Derwent and Howden, which form Ladybower Reservoir, Derwent Reservoir and Howden Reservoir respectively.