Thornaby-on-Tees is a Royal Charter town, civil parish and former Borough within the Borough of Stockton-on-Tees in the ceremonial county of North Yorkshire, England. It is on the south bank of the River Tees, 3 miles (5 kilometres) southeast of Stockton-on-Tees, and 4mi (6km) southwest of Middlesbrough, and has a population of 24,741 according to the 2011 census.