Buck Run is a tributary of Little Muncy Creek in Lycoming County, Pennsylvania, in the United States. It is approximately 1.3 miles (2.1 km) long and flows through Jordan Township. The watershed of the stream has an area of 0.81 square miles (2.1 km2). The surficial geology near the stream mostly consists of Illinoian Till and Illinoian Lag, with some alluvium and bedrock. The stream is a Coldwater Fishery and is being considered for wild trout designation. It has one unnamed tributary.