Heathcote Brook, also called Heathcote Run, is a small river in central New Jersey that flows into the Millstone River. Rising near New Road and Route 1, it passes through a residential area, crosses Route 1 twice, runs for part of its course alongside that highway, and receives several smaller tributaries. It later joins Carters Brook, passes under Heathcote Road, and enters the Millstone River. A branch called Heathcote Brook Branch is part of the same drainage system. Though modest in size, the brook is easily accessible at many road crossings and forms part of the broader Millstone River watershed.