Lake Pedder, Artificial reservoir in southwestern Tasmania, Australia.

Lake Pedder is a reservoir in southwestern Tasmania covering about 242 square kilometres, held back by the Serpentine, Scotts Peak and Edgar dams. The Serpentine dam is a 38-metre-high embankment dam with a concrete upstream face, Scotts Peak is a 43-metre-high embankment dam with a bitumen upstream face, and Edgar is a 17-metre-high embankment dam near Scotts Peak. The flooded basin lies below the Frankland Range.

European surveyors found the original lake during a trigonometric survey in 1835, and John Wedge named it after John Pedder, the first chief justice of Van Diemen's Land. In 1955 the lake and 59,000 surrounding acres were declared a scenic reserve. The Hydro-Electric Commission dammed the Serpentine and Huon rivers in 1972, submerging the lake to form the reservoir.

The reservoir bears the name of Sir John Pedder, Tasmania's first chief justice in the 19th century. Its flooding triggered widespread protests and led to the formation of the world's first green party in 1972.

The area sits remote in southwestern Tasmania and is reached by unsealed roads that can be difficult in poor weather. Visitors should bring enough supplies and fuel, as facilities nearby are limited.

The original lake still lies intact beneath 15 meters (49 feet) of water at the bottom of the present reservoir. Several species, including the Lake Pedder earthworm, vanished after the flooding and are now considered extinct.