Thornaby-on-Tees, commonly referred to as Thornaby, is a town and civil parish located in North Yorkshire, England. It is situated on the south bank of the River Tees within the Borough of Stockton-on-Tees and the broader Tees Valley area.
The town is positioned approximately 3.5 miles (5.6 km) south-east of Middlesbrough and 41 miles (66 km) north of York. According to the 2011 census, the parish had a population of 24,741.