Pathfinder Reservoir is located in the U.S. state of Wyoming on the North Platte River between Casper and Rawlins.

The reservoir was created by Pathfinder Dam and has a storage capacity of 1,016,000 acre-feet (1.253×109 m3).

Much of the water used to serve the 335,000 acre (1360 km2) North Platte Project is stored here.

Some of the water in the reservoir is released to satisfy other water rights and to operate power plants downstream of the reservoir.

Pathfinder Reservoir is the site of the only established population of the Macedonian Ohrid Trout (S. letnica) in the United States.