Thornaby-on-Tees, commonly referred to as Thornaby, is a town and civil parish in the North Yorkshire part of the borough of Stockton-on-Tees, England. The parish had a population of 24,741 at the 2011 census, in the Teesside built-up area. It is located on the south bank of the River Tees. The town was incorporated as a municipal borough in 1892, during the Victorian era. The borough was abolished in 1968 on the creation of the County Borough of Teesside.