Thornleigh Salesian College is a Roman Catholic secondary school in the Astley Bridge area of Bolton in Greater Manchester, England.

Thornleigh College was originally a boys school founded in 1925 by the Salesians of Don Bosco at the request of the Clergy of Bolton.

£4 million of investment in new buildings in the years 1986 to 1989 enabled the whole school to consolidate at Sharples Park from September 1990.

The Latin Motto "Sicut Cervus" is the incipit of Psalm 42, and can be loosely translated as 'As the Hart'.

The Hargreaves were a wealthy Bolton family who owned the house at Sharples Park which was bought by the Salesians when Thornleigh was founded in 1925.