Thornlea is a local service district and designated place in the Canadian province of Newfoundland and Labrador.
Thornlea is in Newfoundland within Subdivision A of Division No. 1.
As a designated place in the 2016 Census of Population conducted by Statistics Canada, Thornlea recorded a population of 115 living in 51 of its 66 total private dwellings, a change of from its 2011 population of 101. With a land area of , it had a population density of in 2016.
Thornlea is a local service district (LSD) that is governed by a committee responsible for the provision of certain services to the community. The chair of the LSD committee is Pat Murphy.