Timber Run is a tributary of Rocky Brook in Mercer County, New Jersey in the United States.

Timber Run starts at 40°15′41″N 74°29′2″W / 40.26139°N 74.48389°W / 40.26139; -74.48389, in a housing development near Franklin Street (SR-33). It flows south and drains into Quad II Lake, which drains into Rocky Brook at 40°15′30″N 74°29′26″W / 40.25833°N 74.49056°W / 40.25833; -74.49056.

Another tributary to Rocky Brook that runs nearby is also called Timber Run. This one starts in the middle of a field between Lake Drive and the original alignment of Milford Rd. It flows west-northwest to a point behind a restaurant located a few hundred feet east of the New Jersey Turnpike. From there, the creek turns west-southwest, and continues until it drains into a narrow recessed section of Peddie Lake. Much of this stream is culverted, and parts of its route are diverted around local businesses and Interchange 8 of the Turnpike.

• List of rivers of New Jersey

• USGS Coordinates in Google Maps