Catoctin Creek is a 14.1-mile-long (22.7 km)[1] tributary of the Potomac River in Loudoun County, Virginia, with a watershed of 59,000 acres (240 km2).

The North Fork Catoctin Creek, 14.5 miles (23.3 km) long,[1] begins at Purcellville Reservoir east of the Blue Ridge Mountains in the Between the Hills valley, near the West Virginia border.

The source of the 18.5-mile-long (29.8 km)[1] South Fork Catoctin Creek is just east of the Blue Ridge's Wilson Gap on the West Virginia border.

The creek flows north along Catoctin Mountain's western side through the village of Taylorstown.

Catoctin Creek continues meandering along the northern edge of Furnace Mountain and empties into the Potomac River to the north of the U.S. Highway 15 bridge across from Point of Rocks, Maryland.